WO2014148027A1 - Light control device, spatial light communication device using same, and light control method - Google Patents

Light control device, spatial light communication device using same, and light control method Download PDF

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Publication number
WO2014148027A1
WO2014148027A1 PCT/JP2014/001493 JP2014001493W WO2014148027A1 WO 2014148027 A1 WO2014148027 A1 WO 2014148027A1 JP 2014001493 W JP2014001493 W JP 2014001493W WO 2014148027 A1 WO2014148027 A1 WO 2014148027A1
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WIPO (PCT)
Prior art keywords
wavefront
light
target
signal
unit
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PCT/JP2014/001493
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French (fr)
Japanese (ja)
Inventor
青木　一彦
想 西村
柳田　美穂
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日本電気株式会社
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Priority to JP2015506603A priority Critical patent/JP6274204B2/en
Publication of WO2014148027A1 publication Critical patent/WO2014148027A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/112—Line-of-sight transmission over an extended range
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/118—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum specially adapted for satellite communication

Definitions

  • the present invention relates to an optical control device, an optical space communication device using the same, and an optical control method, and in particular, an optical control device that suppresses an optical surge without reducing reception sensitivity in optical space communication, and an optical space using the same.
  • the present invention relates to a communication device and an optical control method.
  • laser light is used to communicate a space between moving bodies such as artificial satellites and aircraft, between a moving body and a ground station, or between ground stations.
  • optical space communication it is necessary to align the optical axes of the light beams for transmission between the receiver and the transmitter in order to transmit communication signals.
  • the light beam for transmission spreads at a spread angle corresponding to the wavelength of the laser light. Further, when the light beam passes through the atmosphere, the light intensity is attenuated according to the propagation distance in the atmosphere due to atmospheric absorption or scattering. As a result, the light intensity received by the receiver decreases as the distance from the transmitter increases, and thus it is necessary to improve reception sensitivity.
  • the deflection mechanism provided in the repeater between the transmitter and the receiver controls the deflection of the light beam, while the optical beam amplifier provided in front of the light receiving element
  • An optical space transmission device for amplification is described in Patent Document 1.
  • the optical space transmission device of Patent Literature 1 includes a repeater and a receiver.
  • a converging lens that condenses the light beam from the transmitter, an optical fiber on which the condensed light beam is incident, a collimator lens that collimates the light beam emitted from the optical fiber, And a deflection mechanism provided on the collimator lens side of the optical fiber.
  • a converging lens that collects the light beam from the transmitter or the repeater, an optical fiber on which the collected light beam is incident, and an optical fiber that couples the light beam in the optical fiber and the excitation light It consists of a coupler.
  • the receiver includes an optical fiber amplifier into which the two coupled lights are incident, and a reproduction signal apparatus into which the light beam amplified by the optical fiber amplifier is incident.
  • the light beam emitted from the transmitter is collected by the converging lens of the repeater and enters the optical fiber.
  • the light beam emitted from the optical fiber becomes parallel light by the collimator lens and propagates to the receiver.
  • the collimator lens side of the optical fiber is displaced by a deflection mechanism in a plane perpendicular to the optical axis of the collimator lens so as to enter the end of the optical fiber in the receiver.
  • the light beam propagated from the transmitter or the repeater is collected by the converging lens in the receiver and enters the optical fiber.
  • the light beam incident on the optical fiber coupler is combined with the pump light from the pump light source, the light beam is amplified by the optical fiber amplifier, and is incident on the reproduction signal device. Thereby, it is possible to correct the optical axis shift of the light beam with respect to the optical axis of the receiver and to improve the lowered light receiving sensitivity.
  • Patent Document 2 describes an optical space communication device that corrects wavefront distortion of incident light using a curvature mirror and amplifies received incident light using an optical receiver including an optical fiber amplifier. Yes.
  • the optical space communication device of Patent Document 2 includes a curvature mirror, a plane mirror, a lens, an optical receiver including an optical fiber amplifier, a control unit, and a drive unit, and operates as follows. To do.
  • the wavefront distortion of the incident light is corrected to the output light having a flat wavefront.
  • the emitted light is reflected by the plane mirror toward the lens and is collected on the optical receiver by the lens.
  • the light collected on the optical fiber amplifier provided by the optical receiver is amplified and a light intensity signal is detected.
  • the control unit outputs a drive signal based on the light intensity signal, and the drive unit displaces the curvature distribution of the mirror surface of the curvature mirror based on the drive signal. Thereby, the loss of the light condensed on the optical fiber amplifier is suppressed.
  • EDFA ErbiumEDDoped Fiber Amplifier
  • EDFA ErbiumEDDoped Fiber Amplifier
  • the received light may be momentarily interrupted by an obstacle or the like between the transmitter and the receiver.
  • the input light of the optical fiber amplifier is lost, so that the excitation light accumulates and the energy level of the optical fiber amplifier becomes excessive.
  • the received light recovers in this state, there is a problem that abnormally strong light is output from the optical fiber amplifier due to a large amplification gain, and the photoelectric conversion element in the receiver is damaged.
  • This abnormally strong light is called a light surge, and in the following explanation, the abnormally strong light is described as a light surge.
  • the transmittance of the optical switch arranged on the output side of the communication beam of the optical fiber amplifier is reduced based on the detection of instantaneous interruption of the communication beam input to the optical fiber amplifier.
  • An object of the present invention is to provide a light control device that solves the above-described problem that the cost is increased and the control is complicated when the influence of an optical surge is avoided, and an optical space communication device using the same. And providing a light control method.
  • the light control device of the present invention includes a wavefront modulation unit that controls a wavefront of incident light, a detection unit that acquires intensity information of the incident light, a control unit that determines a target wavefront based on the intensity information, and the incident light Wavefront control means for controlling the wavefront modulation means so that the wavefront is substantially equal to the target wavefront.
  • the light control method of the present invention acquires phase information and intensity information of incident light, determines a target wavefront of the incident light based on the intensity information, and the wavefront of the incident light is substantially the same as the target wavefront.
  • the wavefront of the incident light is controlled so as to be equal.
  • the optical space communication device and the light control method using the same it is possible to avoid the influence of the light surge without increasing the cost and complicating the control.
  • FIG. 1 is a block diagram showing a configuration of a light control apparatus 1 according to the first embodiment of the present invention.
  • the light control device 1 controls the light beam incident on the optical amplification unit 30 at the subsequent stage and suppresses the light surge input to the light receiving unit 35.
  • the light control device 1 includes a detection unit 9, a control unit 11, a wavefront control unit 13, and a wavefront modulation unit 21.
  • the detection unit 9 receives received light that is a light beam incident on the light control device 1, specifically, a part of the light beam (received light) emitted from the wavefront modulation unit 21. Then, the received light intensity that is the intensity information of the light beam is detected, and the received light intensity information signal based on the received light intensity is output to the control unit 11.
  • the received light intensity information signal is a signal that changes in accordance with a change in received light intensity.
  • the control unit 11 receives the light reception intensity information signal from the detection unit 9, detects a decrease in the light reception intensity from the light reception intensity information signal, and determines a target wavefront based thereon.
  • a target aberration signal including information on the target wavefront is output to the wavefront control unit 13, and an optical amplification control signal for stopping or reducing light amplification is output to the subsequent optical amplification unit 30.
  • control unit 11 When the control unit 11 detects a change in the received light intensity included in the received light intensity information signal, the control unit 11 targets information on wavefront aberration that greatly disturbs the wavefront so that the ratio of the light beam input to the optical amplifying unit 30 decreases. It is added to the aberration signal. After that, the wavefront modulation unit 21 gives information on wavefront aberration that gradually reduces the wavefront disturbance.
  • the light beam input to the wavefront modulation unit 21 and further to the optical amplification unit 30 is momentarily interrupted.
  • the light reception intensity decreases and the light reception intensity light shielding time differs.
  • a predetermined threshold is provided for the received light intensity information signal.
  • the threshold value is the ratio of the size of the obstacle to the cross section intersecting the optical axis of the light beam, and the wavefront modulation unit 21 It is determined in advance from the magnitude of the light surge accompanying the momentary interruption of the light beam incident on the light. When the received light intensity information signal is below this threshold, it is detected that the received light intensity has decreased.
  • control unit 11 When the control unit 11 detects the decrease in the received light intensity, the control unit 11 adds information on large wavefront aberrations that can be controlled by the wavefront modulation unit 21 to the target aberration signal and outputs the information to the wavefront control unit 13.
  • the control unit 11 gradually adds information on the wavefront aberration smaller than the wavefront aberration at that time to the target aberration signal to thereby add the wavefront control unit. 13 to output.
  • the information of wavefront aberration which decreases stepwise is added to the target aberration signal until the large wavefront aberration first applied to the light beam becomes zero.
  • the wavefront control unit 13 receives the target aberration signal from the control unit 11 and outputs a phase information signal of the light beam compensated by the wavefront modulation unit 21. Specifically, based on the information on the wavefront aberration included in the target aberration signal, a two-dimensional phase distribution of a cross section perpendicular to the optical axis of the light beam is calculated, and the information is output to the wavefront modulation unit 21 as a phase information signal. To do. That is, when information on large wavefront aberration that can be controlled by the wavefront modulation unit 21 is included in the target aberration signal, a phase information signal that greatly disturbs the wavefront is output to the wavefront modulation unit 21. When the target aberration signal includes wavefront aberration information that gradually decreases, a phase information signal corresponding to the information is output to the wavefront modulation unit 21.
  • the wavefront modulation unit 21 compensates for fluctuations in the wavefront of the light beam due to atmospheric fluctuations. Further, when an instantaneous interruption of the light beam occurs, the spatial phase of the light beam incident on the light control device 1 is modulated and emitted based on the phase information signal from the wavefront control unit 13. That is, the phase of light in a plurality of regions in a two-dimensional plane intersecting the traveling direction of the light beam (the direction incident on the wavefront modulation unit 21) is controlled, and the light beam is emitted or reflected to the light amplification unit 30.
  • the wavefront modulation unit 21 can be a deformable mirror, a liquid crystal panel, or the like.
  • the wavefront modulation unit 21 gives a large wavefront aberration to the light beam based on the signal.
  • the wavefront of the light beam is greatly disturbed, and the ratio of the light beam output to the optical amplifying unit 30 is reduced.
  • the wavefront aberration of the light beam is reduced stepwise based on the signal. Accordingly, the ratio of the light beam output to the optical amplification unit 30 increases stepwise.
  • the light amplification of the light amplifying unit 30 is resumed, whereby the light beam incident on the light amplifying unit 30 is amplified, and the light receiving unit 35 receives the communication signal included in the light beam. To detect.
  • FIG. 2 is a flowchart for explaining a light control method using the light control device 1
  • FIG. 3 is a diagram showing a relationship between a target aberration signal (target wavefront) and a received light intensity information signal (intensity information).
  • FIG. 3 shows a case where the relationship between the target aberration signal and the received light intensity information signal changes linearly, but is not limited to this. Any relationship may be used as long as the target aberration increases and the received light intensity decreases. For example, the relationship between the target aberration signal and the received light intensity information signal may change in a curved line.
  • control unit 11 monitors whether the received light intensity information signal input from detection unit 9 is equal to or less than a threshold value (step S1). When larger than the threshold value (when Step S1 is No), the monitoring of the received light intensity information signal is continued. On the other hand, if it is equal to or less than the threshold value (when Step S1 is Yes), the control unit 11 outputs a target aberration signal that increases wavefront aberration (having information on large wavefront aberration) to the wavefront control unit 13 (Step S2). Specifically, as shown in FIG. 3, a value A N larger than the target aberration signal A 0 when the received light intensity information signal is a threshold value is output.
  • control unit 11 outputs an optical amplification control signal for reducing (stopping or reducing) the amplification of light to the optical amplification unit 30 (step S3). Subsequently, the control unit 11 outputs a target aberration signal for reducing the wavefront aberration (having information for gradually reducing the wavefront aberration) to the wavefront control unit 13 (step S4). At this time, the value of the target aberration signal output to the wavefront control unit 13 is a value A N ⁇ 1 between A N and A 0 . Thereafter, the control unit 11 monitors whether or not the received light intensity information signal input from the detection unit 9 is greater than or equal to a threshold value (step S5).
  • Step S5 When smaller than the threshold value (when Step S5 is No), the process returns to Step S4. At this time, in step S4, the control unit 11 outputs a target aberration signal to which the value A N ⁇ 2 smaller than A N ⁇ 1 and larger than A 0 is given to the wavefront control unit 13. In this way, the target aberration signal to which a value that gradually approaches A 0 from A N is output to the wavefront control unit 13.
  • Step S6 the operation time from step S1 to step S5 of the control unit 11 is set to be longer than the time during which the light beam is momentarily interrupted.
  • the wavefront modulation unit 21 that performs wavefront compensation of the light beam accompanying the fluctuation of the atmosphere to the optical amplification unit 30 as the received light intensity information signal becomes less than the threshold value. Decreasing the input light beam. At the same time, the amplification of the light beam of the light amplifying unit 30 is stopped or reduced. Further, by increasing the light beam input from the wavefront modulation unit 21 to the optical amplification unit 30 by changing the wavefront aberration in a stepwise manner until the received light intensity information signal becomes equal to or greater than the threshold value, the light of the optical amplification unit 30 is increased. Restore beam amplification. Thereby, a new optical element is not required for suppression of the optical surge, and control complexity can be suppressed while suppressing an increase in cost including assembly work.
  • the light beam input to the wavefront modulation unit 21 is momentarily interrupted, it is possible to suppress the occurrence of an optical surge generated in the optical amplification unit 30.
  • the instantaneous interruption of the light beam is recovered, the light beam is efficiently input from the wavefront modulation unit 21 to the optical amplification unit 30 and the light amplification of the optical amplification unit 30 is also recovered. A decrease in sensitivity can be prevented.
  • FIG. 4 is a block diagram showing the configuration of the light control apparatus 2 according to the second embodiment of the present invention.
  • the light control apparatus 2 includes a wavefront calculation unit 14, a light dividing unit 22, a light condensing unit 31, an optical fiber 32, and light in addition to the configuration of the first embodiment.
  • a fiber amplifier 33, an excitation light source 34, and a light receiving unit 35 are provided.
  • the light intensity calculating part 10 and the wavefront sensor 23 which comprise the detection part 9 of 1st Embodiment are provided, the target wavefront calculating part 12 and the wavefront calculating part 14 which comprise the wavefront control part 13 of 1st Embodiment.
  • the light splitting unit 22 splits the light beam subjected to phase modulation into two optical paths.
  • the optical path toward the wavefront sensor 23 and the optical path toward the light condensing unit 31 are divided.
  • a half mirror, a prism, or a polarization beam splitter can be used. Note that the intensity ratios of the divided optical paths are not necessarily equal.
  • the wavefront sensor 23 includes a camera unit such as a CCD (Charge Coupled Device) element or a CMOS (Complementary Metal Oxide Semiconductor) element as a detection unit. Then, the spatial phase distribution of one of the light beams divided by the light dividing unit 22 is measured, and information on the phase distribution is converted into an electrical signal and output. Specifically, the phase information that is information on the phase or the gradient of the phase in a plurality of regions in a two-dimensional plane intersecting the traveling direction of the light beam (the direction of incidence on the wavefront sensor 23) is converted into an electric signal to generate a wavefront. The result is output to the calculation unit 14.
  • a camera unit such as a CCD (Charge Coupled Device) element or a CMOS (Complementary Metal Oxide Semiconductor) element as a detection unit.
  • the spatial phase distribution of one of the light beams divided by the light dividing unit 22 is measured, and information on the phase distribution is converted into an electrical signal and output. Specifically, the
  • the wavefront sensor 23 measures (or detects) the spatial intensity distribution of the incident light beam, converts the intensity distribution information into an electrical signal, and outputs it. Specifically, information on the intensity or gradient of intensity in a plurality of regions in a two-dimensional plane intersecting the traveling direction of the light beam (the direction of incidence on the wavefront sensor 23) is converted into an electrical signal and sent to the light intensity calculation unit 10. Output.
  • a Shack-Hartmann wavefront sensor, a wavefront curvature sensor, or the like can be used as the wavefront sensor 23 as described above.
  • the light intensity calculation unit 10 calculates the received light intensity (intensity information) from the electric signal related to the intensity or intensity gradient information in the two-dimensional plane measured (or detected) by the wavefront sensor 23, and the calculated electric signal of the information Is output to the control unit 11 as a received light intensity information signal.
  • the received light intensity information signal is a signal that changes in accordance with a change in received light intensity.
  • the wavefront calculation unit 14 calculates the wavefront of the light beam from the electrical signal related to the phase or phase slope information (phase information) output from the wavefront sensor 23, and outputs the calculated electrical signal to the wavefront compensation calculation unit 15. .
  • the electrical signal output to the wavefront compensation calculation unit 15 is a signal corresponding to the two-dimensional phase information of the light beam incident on the wavefront sensor 23. It is.
  • the control unit 11 sets a target aberration signal that the wavefront modulation unit 21 gives to the phase of the light beam, and outputs the target aberration signal to the target wavefront calculation unit 12. Further, the target wavefront calculator 12 outputs a phase information signal including information on a two-dimensional phase distribution corresponding to the target aberration based on the input target aberration signal.
  • a light condensing unit 31 to be described later changes a condensing spot formed on the core of the optical fiber 32.
  • the target aberration signal is set so as to change the shape, size, and position of the condensing spot on the incident surface of the optical fiber 32, and is guided into the core diameter on the incident surface of the optical fiber 32.
  • the target aberration signal is set so as to change the shape, size, and position of the focused spot in stages.
  • the wavefront compensation calculation unit 15 calculates the difference between the phase information signal input from the target wavefront calculation unit 12 and the electrical signal related to the calculation information of the wavefront of the light beam input from the wavefront calculation unit 14, and calculates from the information
  • the control signal of the wavefront modulation unit 21 is output. Specifically, the wavefront modulation unit 21 is feedback-controlled so that the difference between the phase information related to the target wavefront of the light beam and the phase information related to the wavefront of the light beam measured by the wavefront sensor 23 becomes small. As a result, the wavefront of the light beam emitted from the wavefront modulation unit 21 is changed to the wavefront of the desired light beam.
  • the calculation in the wavefront compensation calculation unit is a matrix calculation including a conversion matrix.
  • the light condensing unit 31 condenses the light beam traveling in the direction of the optical fiber 32 among the light beams divided by the light dividing unit 22, and the collected light beam enters the core of the optical fiber 32.
  • the focused spot diameter on the optical fiber is close to the core diameter of the optical fiber and ideally equal to the core diameter, the desired optical communication performance can be achieved.
  • the optical fiber 32 is connected to the optical fiber amplifier 33.
  • the optical fiber amplifier 33 is an optical element that improves the light receiving sensitivity of the communication signal of the optical space communication, and changes the intensity of the light beam incident and guided to the optical fiber 32 according to the excitation light injected from the excitation light source 34. And output to the light receiving unit 35. Specifically, when the excitation light from the excitation light source 34 is injected into the optical fiber amplifier, the light beam incident from the optical fiber 32 is amplified and emitted to the light receiving unit 35. When the excitation light is not injected into the optical fiber amplifier, the light beam incident from the optical fiber 32 is emitted to the light receiving unit without being amplified.
  • the light receiving unit 35 is a photoelectric conversion element such as a photodiode, converts the incident light beam from the optical fiber amplifier 33 into an electrical signal, and outputs it as a received signal to a subsequent circuit.
  • the received light intensity information signal detected by the wavefront sensor 23 decreases.
  • the size, shape, or position of the focused beam with respect to the core on the incident surface of the optical fiber 32 changes or moves, and the coupling efficiency of the light beam incident on the optical fiber decreases.
  • the received light intensity information signal detected by the wavefront sensor 23 is increased stepwise.
  • the size, shape, or position of the focused beam is changed or moved to the diameter and position of the core on the incident surface of the optical fiber 32, and the coupling efficiency of the light beam incident on the optical fiber 32 is improved.
  • the light control device 2 is similar to the first embodiment in that the wavefront modulation unit can be used even if there is a wavefront distortion or wavefront fluctuation of the incident light beam.
  • the wavefront of the light beam is compensated by 21 and the coupling efficiency of the light beam incident on the optical fiber 32 is maintained. Thereby, the fall of the light reception sensitivity at the time of optical communication can be suppressed, and desired communication performance can be achieved.
  • FIG. 5 is a flowchart for explaining the operation of the light control device 2
  • FIG. 6 is a diagram showing the relationship between the target aberration signal and the received light intensity information signal.
  • the received light intensity information signal decreases as the target aberration signal based on spherical aberration increases, and the received light intensity information signal increases as the target aberration signal decreases based on spherical aberration.
  • FIG. 6 shows the case where the target aberration signal is spherical aberration
  • the present invention is not limited to this, and other aberrations such as coma and astigmatism may be used.
  • it may be a wavefront corresponding to an arbitrary coefficient when the wavefront is expanded by a Zernike polynomial, or may be a combination of wavefronts combining them.
  • the control unit 11 has a light reception intensity information signal (intensity information) from the light intensity calculation unit 10 based on the light reception intensity measured by the wavefront sensor 23 equal to or less than a threshold value. Whether or not there is is monitored (step S11).
  • the received light intensity information signal is larger than the threshold (when Step S1 is No)
  • the received light intensity information signal is continuously monitored.
  • the control unit 11 outputs a target aberration signal that increases spherical aberration (having information on large spherical aberration) to the target wavefront calculation unit 12. (Step S12).
  • a value B N greater than the wavefront aberration information B 0 of the target aberration signal when the received light intensity information signal is a threshold value is output.
  • the control unit 11 outputs an optical amplification control signal for reducing (stopping or reducing) the light amplification to the excitation light source 34 (step S13).
  • the control unit 11 outputs a target aberration signal for reducing the spherical aberration (having information for gradually reducing the spherical aberration) to the target wavefront calculation unit 12 (step S14).
  • the value of the target aberration signal output to the target wavefront calculator 12 is a value B N ⁇ 1 between B N and B 0 .
  • the controller 11 monitors whether or not the received light intensity information signal input from the light intensity calculator 10 is equal to or greater than a threshold (step S15). In other words, it is monitored whether the coupling efficiency of the light beam focused on the optical fiber 32 is equal to or higher than a predetermined threshold value.
  • Step S14 the control unit 11 outputs the target aberration signal to which the value B N ⁇ 2 smaller than B N ⁇ 1 and larger than B 0 is given to the target wavefront calculation unit 12.
  • the target wavefront computing unit 12 applies the phase distribution to the light beam created based on this signal every time the information B N , B N-1 , B N-2 added to the target aberration signal is input. Is output to the wavefront compensation calculation unit 15.
  • the wavefront compensation calculation unit 15 calculates the difference between the target aberration signal from the target wavefront calculation unit 12 and the electric signal related to the wavefront of the light beam from the wavefront calculation unit 14, and calculates the wavefront modulation unit calculated from the information 21 control signals are output.
  • Step S15 When the received light intensity information signal is equal to or greater than the threshold value (when Step S15 is Yes), that is, when the light beam coupling efficiency is equal to or greater than the threshold value, the control unit 11 resumes or restores the light amplification. That is, an optical amplification control signal for recovering the emission of the excitation light is output to the excitation light source 34 (step S16). Thereafter, optical space communication is resumed.
  • the wavefront modulation unit 21 adds aberration to the light beam and disturbs the wavefront, thereby shifting to the optical fiber 32. This reduces the coupling efficiency of the light beam. At the same time, the emission of the excitation light to the excitation light source 34 is stopped or reduced. Further, after improving the distorted wavefront by the wavefront modulation unit 21 stepwise until the received light intensity information signal becomes equal to or greater than the threshold value, the emission of the excitation light to the excitation light source 34 is resumed.
  • This operation is realized by a component for wavefront compensation that performs wavefront compensation of a light beam caused by atmospheric fluctuations and a component for optical amplification that improves the light receiving sensitivity. Therefore, while improving the light receiving sensitivity during optical space communication, it is possible to suppress the addition of components for suppressing optical surges, the increase in man-hours for assembly work accompanying the addition, and the addition of control steps for the added components it can.
  • the light beam incident on the wavefront modulation unit 21 is momentarily interrupted, it is possible to prevent the excitation light from being accumulated in the optical fiber amplifier 33 and the energy from being output to the light receiving unit 35 as an optical surge. Further, when the wave front disturbance of the light beam is recovered, the light beam focused on the optical fiber 32 is efficiently incident and the emission of the excitation light from the excitation light source 34 is resumed, so that the light receiving sensitivity during optical communication is reduced. None do.
  • the spherical aberration is gradually improved and the light amplification control signal to be restarted after the received light intensity information signal becomes equal to or higher than the threshold value is output to the excitation light source 34.
  • the present invention is not limited to this.
  • an optical amplification control signal for gradually improving the spherical aberration and gradually amplifying the excitation light may be output to the excitation light source 34.
  • FIG. 7 is a block diagram showing the configuration of the light control apparatus 3 according to the third embodiment of the present invention.
  • the light control device 3 of the third embodiment has a configuration in which a protection time timer 16 is added to the light control device 2 of the second embodiment, and the control unit 11 of the third embodiment is the second embodiment. A function is added to the control unit 11.
  • Other components are the same as those of the light control device 2 of the second embodiment, and a description thereof will be omitted.
  • control unit 11 outputs a target aberration signal and an optical amplification control signal based on the received light intensity information signal from light intensity calculation unit 10.
  • a start signal including protection time start information is output to the protection time timer 16
  • an end signal including protection time end information is input from the protection time timer 16.
  • the protection time is the time from the time when the amplification of light by the excitation light source 34 is stopped or reduced by the optical amplification control signal to the time when the energy of the excitation light accumulated in the optical fiber amplifier 33 is spontaneously emitted.
  • the increased target wavefront aberration is maintained and is not reduced stepwise.
  • the protection time timer 16 receives an activation signal from the control unit 11 and activates the timer according to the signal. After reaching the predetermined protection time after the timer is started, an end signal including information on the end of the protection time is output.
  • FIG. 8 is a flowchart for explaining the operation of the light control device 3. Further, in the flowchart of the light control device 3 of the third embodiment, a protection time timer activation and completion flow are added to the flowchart of the light control device 2 of the second embodiment. The other flow is the same as the flow of the light control device 3 of the second embodiment, and a description thereof will be omitted.
  • the target aberration signal is a signal set based on spherical aberration.
  • control part 11 implements the flow from step S11 to step S13 during optical space communication. Then, the control part 11 outputs the starting signal containing the start information of protection time to the protection time timer 16 (step S20). Next, the control unit 11 monitors whether or not an end signal including end information of the protection time is input (step 21). If there is no input of the end signal (No in step 21), the monitoring of the input of the end signal is continued. On the other hand, when there is an input of an end signal (when step 21 is Yes), the process proceeds to the next step. Thereafter, the flow from step S14 to step S16 is executed.
  • the protection time timer 16 by providing the protection time timer 16, the energy accumulated in the optical fiber amplifier 33 is spontaneously released while suppressing the input of excitation light during the protection time. be able to. For this reason, generation
  • the value of the target aberration signal is changed in a stepwise manner (spherical aberration is reduced in a stepwise manner). It is not limited to.
  • the target aberration signal may be changed from a large value to a small value at a time.
  • the small value of the target aberration signal may be a value before it falls below the threshold value of the received light intensity information signal.
  • FIG. 9 is a block diagram showing the configuration of the light control device 4 according to the fourth embodiment of the present invention.
  • the light control device 4 of the fourth embodiment has a configuration in which a wavefront storage unit 17 is added to the light control device 2 of the second embodiment, and the control unit 11 of the fourth embodiment is the second embodiment. A function is added to the control unit 11.
  • Other components are the same as those of the light control device 2 of the second embodiment, and a description thereof will be omitted.
  • the wavefront recording unit 17 stores the light intensity signal detected by the light receiving unit 35 and the wavefront information calculated by the wavefront calculating unit 14 as the wavefront at the moment when the light intensity signal is reduced. . Specifically, when the light intensity information signal of the wavefront sensor 23 decreases, that is, when the coupling efficiency of the light beam to the optical fiber 32 is low, for each value of the light intensity signal that increases or decreases, The value and the corresponding wavefront information are stored. The stored wavefront information is output to the control unit 11 as target wavefront information.
  • the wavefront when the received light intensity information signal of the wavefront sensor 23 is lowered is the wavefront information calculated by the wavefront calculator 14 when the coupling efficiency of the light beam to the optical fiber 32 is low, is the wavefront during optical space communication.
  • store while performing the wavefront compensation of a light beam using the calculating part 14.
  • the present invention is not limited to this.
  • information on the wavefront calculated by the wavefront calculating unit 14 may be stored.
  • the control unit 11 inputs the received light intensity information signal from the light intensity calculation unit 10 and the wavefront information from the wavefront storage unit 17.
  • the wavefront information input from the wavefront storage unit 17 is used as the target aberration signal.
  • an optical amplification control signal for stopping the amplification of light is output to the optical amplification unit 30.
  • step S12 and step S14 of the light control method of the light control apparatus 2 the wavefront information input from the wavefront storage unit 17 is used as a target aberration signal for improving or improving the spherical aberration.
  • the other flow is the same as the light control method using the light control device 2.
  • the wavefront when the light reception intensity information signal of the wavefront sensor 23 is lowered based on the light intensity signal detected by the light receiving unit 35 affected by the light surge that is, Wavefront information when the coupling efficiency of the light beam to the optical fiber 32 is low can be set as the target aberration.
  • the influence by an optical surge can be suppressed further.
  • an acquisition tracking unit may be provided in the preceding stage of the wavefront modulation unit 21. That is, the light beam captured and tracked by the capture and tracking unit is incident on the wavefront modulation unit 21.
  • the capture tracking unit includes, for example, a gimbal mirror, a steering mirror, an area sensor, a quadrant sensor, and the like.
  • the gimbal mirror roughly controls the directivity direction of the space optical communication device equipped with the light control device described in the second to third embodiments in a wide area.
  • the steering mirror controls the pointing direction of the optical space communication device with high accuracy in a narrow area.
  • the area sensor roughly detects the directivity direction of the space optical communication apparatus in a wide area from the incident light beam.
  • the quadrant sensor detects the directivity direction of the optical space communication device from the incident light beam with high accuracy in a narrow area.
  • FIG. 10 is a block diagram showing the configuration of the light control device 5 and the optical space communication device according to the fifth embodiment of the present invention.
  • the light control device 5 of the fifth embodiment has the same configuration as the light control device 2 of the second embodiment, and the optical space communication device of the fifth embodiment is the light control device 2 of the second embodiment.
  • a capture tracking unit 24 is added.
  • the control unit 11 and the light intensity calculation unit 18 of the fifth embodiment are different from the control unit 11 and the light intensity calculation unit 10 of the second embodiment.
  • Other components are the same as those of the light control device 2 of the second embodiment, and a description thereof will be omitted.
  • the capture tracking unit 24 has the above-described configuration and function. Further, the light beam incident on the capture tracking unit 24 is detected by an area sensor or a four-divided sensor. An electrical signal having information on the detected light intensity distribution is output to the light intensity calculation unit 18.
  • the light intensity calculation unit 18 receives an electrical signal from the capture tracking unit 24, calculates the received light intensity, and outputs a received light intensity information signal including the information to the control unit 11.
  • the wavefront sensor 23 of the fifth embodiment includes information on the phase or the gradient of the phase of a plurality of regions in a two-dimensional plane that intersects the traveling direction of the light beam (the direction of incidence on the wavefront sensor 23). Only the electrical signal is output to the wavefront computing unit 14.
  • the received light intensity is calculated based on the information of the light intensity distribution acquired by the light receiving sensor (for example, the area sensor or the four-divided sensor) of the acquisition and tracking unit having a spatial resolution lower than that of the wavefront sensor 23 using the CCD element or the CMOS element. Calculate. Therefore, the calculation amount of the light intensity calculation unit can be reduced from the second embodiment to the fourth embodiment.
  • the light receiving sensor for example, the area sensor or the four-divided sensor
  • step S3 after the control unit 11 outputs an optical amplification control signal for stopping or reducing the amplification of light (step S3 in the first embodiment, in step S13 of the second to fourth embodiments, the control signal 11 outputs a target aberration signal for improving wavefront aberration (or spherical aberration) (steps S4 and second of the first embodiment).
  • step S14 the control unit 11 may insert a step of monitoring whether the received light intensity information signal is equal to or less than a threshold value.

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Abstract

Costs increase and control becomes complicated when trying to avoid the effects of light surges, therefore this light control device comprises: a wavefront modulation means that controls the wavefront of incident light; a detection means that obtains incident light intensity information; a control means that determines a target wavefront on the basis of the intensity information; and a wavefront control means that controls the wavefront modulation means such that the incident light wavefront becomes substantially equal to the target wavefront.

Description

光制御装置、それを用いた光空間通信装置および光制御方法Light control device, space optical communication device using the same, and light control method
本発明は、光制御装置、それを用いた光空間通信装置および光制御方法に関し、特に、光空間通信における受信感度を低下させることなく光サージを抑制する光制御装置、それを用いた光空間通信装置および光制御方法に関する。 The present invention relates to an optical control device, an optical space communication device using the same, and an optical control method, and in particular, an optical control device that suppresses an optical surge without reducing reception sensitivity in optical space communication, and an optical space using the same. The present invention relates to a communication device and an optical control method.
光空間通信は、レーザ光を用いて、人工衛星や航空機などの移動体間や移動体と地上局との間、あるいは、地上局間の空間を通信するものである。 In optical space communication, laser light is used to communicate a space between moving bodies such as artificial satellites and aircraft, between a moving body and a ground station, or between ground stations.
この光空間通信では、通信信号を伝送するために受信器と送信器との伝送用の光ビームの光軸を合わせる必要がある。また、光空間通信では、伝送用の光ビームはレーザ光の波長に応じた拡がり角で拡がる。また、光ビームが大気中を通過する際に、大気の吸収や散乱などにより、大気中の伝搬距離に応じて光強度が減衰する。その結果、受信器で受信する光強度は、送信器との間の距離が遠くなるほど低下するため、受信感度の向上が必要となる。 In this optical space communication, it is necessary to align the optical axes of the light beams for transmission between the receiver and the transmitter in order to transmit communication signals. In optical space communication, the light beam for transmission spreads at a spread angle corresponding to the wavelength of the laser light. Further, when the light beam passes through the atmosphere, the light intensity is attenuated according to the propagation distance in the atmosphere due to atmospheric absorption or scattering. As a result, the light intensity received by the receiver decreases as the distance from the transmitter increases, and thus it is necessary to improve reception sensitivity.
この問題を解決するために、送信器と受信器との間にある中継器に備えた偏向機構によって、光ビームの偏向を制御しつつ、受光素子の前に供えた光ファイバアンプで光ビームを増幅する光空間伝送装置が特許文献１に記載されている。これにより、送信器から放射される光ビームを受信器内の受光素子で損失を少なく受光することを可能としている。 To solve this problem, the deflection mechanism provided in the repeater between the transmitter and the receiver controls the deflection of the light beam, while the optical beam amplifier provided in front of the light receiving element An optical space transmission device for amplification is described in Patent Document 1. As a result, the light beam emitted from the transmitter can be received by the light receiving element in the receiver with little loss.
特許文献１の光空間伝送装置は、中継器と受信器とを備える。この中継器内は、送信器からの光ビームを集光する収束レンズと、集光された光ビームが入射する光ファイバと、光ファイバから出射された光ビームを平行光とするコリメータレンズと、光ファイバのコリメータレンズ側に設けた偏向機構とから構成されている。受信器内は、送信器あるいは中継器からの光ビームを集光する収束レンズと、集光された光ビームが入射する光ファイバと、光ファイバ内の光ビームと励起光とを結合する光ファイバカプラとから構成されている。さらに、受信器内は、結合した２つの光が入射する光ファイバアンプと、光ファイバアンプによって増幅された光ビームが入射する再生信号器とを備えている。以上の構成により、以下のように動作する。 The optical space transmission device of Patent Literature 1 includes a repeater and a receiver. In this repeater, a converging lens that condenses the light beam from the transmitter, an optical fiber on which the condensed light beam is incident, a collimator lens that collimates the light beam emitted from the optical fiber, And a deflection mechanism provided on the collimator lens side of the optical fiber. In the receiver, a converging lens that collects the light beam from the transmitter or the repeater, an optical fiber on which the collected light beam is incident, and an optical fiber that couples the light beam in the optical fiber and the excitation light It consists of a coupler. Further, the receiver includes an optical fiber amplifier into which the two coupled lights are incident, and a reproduction signal apparatus into which the light beam amplified by the optical fiber amplifier is incident. With the above configuration, the operation is as follows.
送信器から出射した光ビームは中継器の収束レンズで集光され光ファイバに入射する。光ファイバから出射した光ビームはコリメータレンズによって平行光となり、受信器へ伝播する。受信器内の光ファイバ端部に入射するように、コリメータレンズの光軸に直交する面内において、偏向機構により光ファイバのコリメータレンズ側を変位させる。また、送信器、あるいは、中継器より伝搬した光ビームは受信器内の収束レンズによって集光され光ファイバに入射する。光ファイバカプラにおいて入射した光ビームは励起光源からの励起光と結合し、光ファイバアンプによって光ビームが増幅され、再生信号器に入射する。これにより、受信器の光軸に対する光ビームの光軸ずれを補正するとともに、低下した受光感度を向上することができる。 The light beam emitted from the transmitter is collected by the converging lens of the repeater and enters the optical fiber. The light beam emitted from the optical fiber becomes parallel light by the collimator lens and propagates to the receiver. The collimator lens side of the optical fiber is displaced by a deflection mechanism in a plane perpendicular to the optical axis of the collimator lens so as to enter the end of the optical fiber in the receiver. In addition, the light beam propagated from the transmitter or the repeater is collected by the converging lens in the receiver and enters the optical fiber. The light beam incident on the optical fiber coupler is combined with the pump light from the pump light source, the light beam is amplified by the optical fiber amplifier, and is incident on the reproduction signal device. Thereby, it is possible to correct the optical axis shift of the light beam with respect to the optical axis of the receiver and to improve the lowered light receiving sensitivity.
しかし、光空間通信では、大気のゆらぎにより光ビームの波面が変動することによって、受信器への結合効率が変化し、受信レベルが変動する。この結果、通信品質が低下し、場合によっては通信が不可能となる。 However, in optical space communication, the wavefront of the light beam fluctuates due to atmospheric fluctuations, so that the coupling efficiency to the receiver changes and the reception level fluctuates. As a result, the communication quality deteriorates and communication is impossible in some cases.
この問題を解決するために、曲率ミラーによって入射光の波面歪を補正し、光ファイバアンプを備えた光受信機によって、受信した入射光を増幅する光空間通信装置が特許文献２に記載されている。 In order to solve this problem, Patent Document 2 describes an optical space communication device that corrects wavefront distortion of incident light using a curvature mirror and amplifies received incident light using an optical receiver including an optical fiber amplifier. Yes.
特許文献２の光空間通信装置は、曲率ミラーと、平面ミラーと、レンズと、光ファイバアンプを備えた光受信機と、制御部と、駆動部とから構成されており、以下のように動作する。 The optical space communication device of Patent Document 2 includes a curvature mirror, a plane mirror, a lens, an optical receiver including an optical fiber amplifier, a control unit, and a drive unit, and operates as follows. To do.
曲率ミラーのミラー面の曲率分布を可変することで、入射光の波面歪を平坦な波面の出射光に補正する。出射光は平面ミラーによってレンズに向けて反射し、レンズによって光受信機上に集光する。光受信機が供えた光ファイバアンプへ集光した光は増幅され、光強度信号が検出される。制御部はこの光強度信号に基づいて駆動信号を出力し、駆動部はこの駆動信号に基づいて曲率ミラーのミラー面の曲率分布を変位させる。これにより、光ファイバアンプへ集光する光の損失を抑制している。 By varying the curvature distribution of the mirror surface of the curvature mirror, the wavefront distortion of the incident light is corrected to the output light having a flat wavefront. The emitted light is reflected by the plane mirror toward the lens and is collected on the optical receiver by the lens. The light collected on the optical fiber amplifier provided by the optical receiver is amplified and a light intensity signal is detected. The control unit outputs a drive signal based on the light intensity signal, and the drive unit displaces the curvature distribution of the mirror surface of the curvature mirror based on the drive signal. Thereby, the loss of the light condensed on the optical fiber amplifier is suppressed.
なお、光ファイバアンプとしては、エルビウムドープトファイバ増幅器（ＥＤＦＡ：Erbium Doped Fiber Amplifier）が用いられている。これは、石英ファイバに３価のエルビウムイオンが添加され、波長が０．９８μｍまたは１．４８μｍの光で励起することで、１．５５μｍ帯の受信光に対して増幅作用を示す。 An erbium-doped fiber amplifier (EDFA: ErbiumＥＤDoped Fiber Amplifier) is used as the optical fiber amplifier. This is because a trivalent erbium ion is added to a quartz fiber and excited with light having a wavelength of 0.98 μm or 1.48 μm, thereby amplifying the received light in the 1.55 μm band.
特開平０７－０９９４８０号公報Japanese Patent Laid-Open No. 07-099480 特開平１０－２３９６００号公報JP-A-10-239600
しかし、光空間通信では、送信機と受信機との間の障害物等により受信光が瞬断することがある。受信光の瞬断が発生すると、光ファイバアンプの入力光が失われるため、励起光が蓄積して光ファイバアンプのエネルギーレベルが過大となる。その状態で受信光が回復した場合、大きな増幅利得により異常に強い光が光ファイバアンプから出力され、受信機内の光電変換素子が破損するという問題がある。この異常に強い光は光サージと呼ばれ、以降の説明では異常に強い光を光サージと記載する。 However, in optical space communication, the received light may be momentarily interrupted by an obstacle or the like between the transmitter and the receiver. When the instantaneous interruption of the received light occurs, the input light of the optical fiber amplifier is lost, so that the excitation light accumulates and the energy level of the optical fiber amplifier becomes excessive. When the received light recovers in this state, there is a problem that abnormally strong light is output from the optical fiber amplifier due to a large amplification gain, and the photoelectric conversion element in the receiver is damaged. This abnormally strong light is called a light surge, and in the following explanation, the abnormally strong light is described as a light surge.
このような問題に対し、光ファイバ通信の分野では、光ファイバアンプへ入力する通信ビームの瞬断の検出に基づいて、光ファイバアンプの通信ビームの出力側に配置した光スイッチの透過率を低下させることで、光サージによる受光素子の破損を防ぐ技術がある。 In response to such problems, in the field of optical fiber communication, the transmittance of the optical switch arranged on the output side of the communication beam of the optical fiber amplifier is reduced based on the detection of instantaneous interruption of the communication beam input to the optical fiber amplifier. By doing so, there is a technique for preventing damage to the light receiving element due to light surge.
しかし、光サージを抑制するために、光学系へ光学素子である光スイッチを新たに挿入する必要がある。それに伴って受信する光ビームの光学損失が生じるだけでなく、光スイッチを含めた複雑な制御が必要である。 However, in order to suppress the optical surge, it is necessary to newly insert an optical switch as an optical element into the optical system. Accordingly, not only optical loss of the received light beam occurs, but also complicated control including an optical switch is required.
このように、光空間通信装置において光サージによる影響を回避しようとすると、新たな部品を追加するために、組立工程も含めた製造コストが増大するだけでなく、制御が複雑化するという問題があった。 As described above, in order to avoid the influence of the optical surge in the optical space communication device, there is a problem that not only the manufacturing cost including the assembly process increases but also the control becomes complicated in order to add a new part. there were.
本発明の目的は、上述した課題である、光サージによる影響を回避しようとすると、コストが増大し、制御が複雑化する、という課題を解決する光制御装置、それを用いた光空間通信装置および光制御方法を提供することにある。 An object of the present invention is to provide a light control device that solves the above-described problem that the cost is increased and the control is complicated when the influence of an optical surge is avoided, and an optical space communication device using the same. And providing a light control method.
本発明の光制御装置は、入射光の波面を制御する波面変調手段と、前記入射光の強度情報を取得する検出手段と、前記強度情報に基づいて目標波面を定める制御手段と、前記入射光の波面が前記目標波面と略等しくなるように、前記波面変調手段を制御する波面制御手段、とを備える。 The light control device of the present invention includes a wavefront modulation unit that controls a wavefront of incident light, a detection unit that acquires intensity information of the incident light, a control unit that determines a target wavefront based on the intensity information, and the incident light Wavefront control means for controlling the wavefront modulation means so that the wavefront is substantially equal to the target wavefront.
また、本発明の光制御方法は、入射光の位相情報と強度情報とを取得し、前記強度情報に基づいて前記入射光の目標波面を決定し、前記入射光の波面が前記目標波面と略等しくなるように、前記入射光の波面を制御する。 The light control method of the present invention acquires phase information and intensity information of incident light, determines a target wavefront of the incident light based on the intensity information, and the wavefront of the incident light is substantially the same as the target wavefront. The wavefront of the incident light is controlled so as to be equal.
本発明の光制御装置、それを用いた光空間通信装置および光制御方法によれば、コストの増大、および、制御の複雑化を招くことなく、光サージによる影響を回避することができる。 According to the light control device of the present invention, the optical space communication device and the light control method using the same, it is possible to avoid the influence of the light surge without increasing the cost and complicating the control.
本発明の第１の実施形態による光制御装置の構成を示すブロック図である。It is a block diagram which shows the structure of the light control apparatus by the 1st Embodiment of this invention. 本発明の第１の実施形態による光制御装置の動作を説明するためのフローチャートである。It is a flowchart for demonstrating operation | movement of the light control apparatus by the 1st Embodiment of this invention. 本発明の第１の実施形態による光制御装置における目標収差と受光強度情報信号の関係を示す図である。It is a figure which shows the relationship between the target aberration and the light reception intensity information signal in the light control apparatus by the 1st Embodiment of this invention. 本発明の第２の実施形態による光制御装置の構成を示すブロック図である。It is a block diagram which shows the structure of the light control apparatus by the 2nd Embodiment of this invention. 本発明の第２の実施形態による光制御装置の動作を説明するためのフローチャートである。It is a flowchart for demonstrating operation | movement of the light control apparatus by the 2nd Embodiment of this invention. 本発明の第２の実施形態による光制御装置における球面収差と受光強度情報信号（光ファイバへの結合効率）の関係を示す模式図である。It is a schematic diagram which shows the relationship between the spherical aberration and the light reception intensity information signal (coupling efficiency to an optical fiber) in the light control apparatus by the 2nd Embodiment of this invention. 本発明の第３の実施形態による光制御装置の構成を示すブロック図である。It is a block diagram which shows the structure of the light control apparatus by the 3rd Embodiment of this invention. 本発明の第３の実施形態による光制御装置の動作を説明するためのフローチャートである。It is a flowchart for demonstrating operation | movement of the light control apparatus by the 3rd Embodiment of this invention. 本発明の第４の実施形態による光制御装置の構成を示すブロック図である。It is a block diagram which shows the structure of the light control apparatus by the 4th Embodiment of this invention. 本発明の第５の実施形態による光制御装置の構成を示すブロック図である。It is a block diagram which shows the structure of the light control apparatus by the 5th Embodiment of this invention.
〔第１の実施形態〕以下、図面を参照して本発明の第１の実施形態について詳細に説明する。図１は本発明の第１の実施形態による光制御装置１の構成を示すブロック図である。光制御装置１は、後段の光増幅部３０へ入射する光ビームを制御し、受光部３５に入力する光サージを抑制する。 [First Embodiment] Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a light control apparatus 1 according to the first embodiment of the present invention. The light control device 1 controls the light beam incident on the optical amplification unit 30 at the subsequent stage and suppresses the light surge input to the light receiving unit 35.
図１を参照して、本発明の第１の実施形態の光制御装置１の構成を説明する。 With reference to FIG. 1, the structure of the light control apparatus 1 of the 1st Embodiment of this invention is demonstrated.
本発明の第１の実施形態の光制御装置１は、検出部９と制御部１１と波面制御部１３と波面変調部２１とを備える。 The light control device 1 according to the first embodiment of the present invention includes a detection unit 9, a control unit 11, a wavefront control unit 13, and a wavefront modulation unit 21.
検出部９は、光制御装置１へ入射する光ビームである受信光、具体的には波面変調部２１から出射する光ビーム（受信光）の一部を受光する。そして、光ビームの強度情報である受光強度を検出し、受光強度に基づいた受光強度情報信号を制御部１１へ出力する。なお、受光強度情報信号は受光強度の変化に応じて変化する信号である。 The detection unit 9 receives received light that is a light beam incident on the light control device 1, specifically, a part of the light beam (received light) emitted from the wavefront modulation unit 21. Then, the received light intensity that is the intensity information of the light beam is detected, and the received light intensity information signal based on the received light intensity is output to the control unit 11. The received light intensity information signal is a signal that changes in accordance with a change in received light intensity.
制御部１１は、検出部９からの受光強度情報信号を入力し、受光強度情報信号から受光強度の低下を検出し、それに基づいて目標波面を決定する。目標波面に関する情報を含む目標収差信号を波面制御部１３へ出力するとともに、光の増幅を停止あるいは低下させる光増幅制御信号を後段の光増幅部３０へ出力する。 The control unit 11 receives the light reception intensity information signal from the detection unit 9, detects a decrease in the light reception intensity from the light reception intensity information signal, and determines a target wavefront based thereon. A target aberration signal including information on the target wavefront is output to the wavefront control unit 13, and an optical amplification control signal for stopping or reducing light amplification is output to the subsequent optical amplification unit 30.
なお、制御部１１は、受光強度情報信号に含まれる受光強度の変化を検出したとき、光増幅部３０に入力する光ビームの割合が低下するように、波面を大きく乱す波面収差の情報を目標収差信号に付与する。その後、波面変調部２１によって波面の乱れを段階的に減少させる波面収差の情報を付与する。 When the control unit 11 detects a change in the received light intensity included in the received light intensity information signal, the control unit 11 targets information on wavefront aberration that greatly disturbs the wavefront so that the ratio of the light beam input to the optical amplifying unit 30 decreases. It is added to the aberration signal. After that, the wavefront modulation unit 21 gives information on wavefront aberration that gradually reduces the wavefront disturbance.
光ビームの伝搬光路に障害物が侵入すると、波面変調部２１、さらには、光増幅部３０へ入力する光ビームが瞬断される。光ビームの光軸に直交する断面における障害物の大きさ、障害物が光路を遮る時間に応じて、受光強度の低下、受光強度の遮光時間が異なる。 When an obstacle enters the propagation path of the light beam, the light beam input to the wavefront modulation unit 21 and further to the optical amplification unit 30 is momentarily interrupted. Depending on the size of the obstacle in the cross section orthogonal to the optical axis of the light beam and the time during which the obstacle blocks the optical path, the light reception intensity decreases and the light reception intensity light shielding time differs.
ここで、受光強度情報信号に対し所定の閾値を設ける。光増幅部３０へ入力する光ビームの瞬断が開始されたことを瞬時に検知するために、閾値は、光ビームの光軸に交差する断面に対する障害物の大きさの割合、波面変調部２１へ入射する光ビームの瞬断に伴う光サージの大きさなどから予め定めておく。受光強度情報信号がこの閾値以下となる場合、受光強度が低下したと検知する。 Here, a predetermined threshold is provided for the received light intensity information signal. In order to instantaneously detect that the instantaneous interruption of the light beam input to the optical amplification unit 30 has been started, the threshold value is the ratio of the size of the obstacle to the cross section intersecting the optical axis of the light beam, and the wavefront modulation unit 21 It is determined in advance from the magnitude of the light surge accompanying the momentary interruption of the light beam incident on the light. When the received light intensity information signal is below this threshold, it is detected that the received light intensity has decreased.
制御部１１は、この受光強度の低下を検知した時、波面変調部２１において制御可能な大きな波面収差の情報を目標収差信号に付与して波面制御部１３へ出力する。 When the control unit 11 detects the decrease in the received light intensity, the control unit 11 adds information on large wavefront aberrations that can be controlled by the wavefront modulation unit 21 to the target aberration signal and outputs the information to the wavefront control unit 13.
また、波面変調部２１によって光ビームに大きな波面収差が付与されている時、制御部１１は、そのときの波面収差より小さい波面収差の情報を段階的に目標収差信号に付与して波面制御部１３へ出力する。ここで、最初に光ビームへ付与した大きな波面収差がゼロとなるまで、段階的に減少する波面収差の情報を目標収差信号に付与する。 Further, when a large wavefront aberration is imparted to the light beam by the wavefront modulation unit 21, the control unit 11 gradually adds information on the wavefront aberration smaller than the wavefront aberration at that time to the target aberration signal to thereby add the wavefront control unit. 13 to output. Here, the information of wavefront aberration which decreases stepwise is added to the target aberration signal until the large wavefront aberration first applied to the light beam becomes zero.
波面制御部１３は、制御部１１からの目標収差信号を入力し、波面変調部２１が補償する光ビームの位相情報信号を出力する。具体的には、目標収差信号に含まれる波面収差の情報に基づき、光ビームの光軸に直交する断面の２次元の位相分布を演算し、その情報を位相情報信号として波面変調部２１へ出力する。つまり、波面変調部２１で制御可能な大きな波面収差の情報を目標収差信号に含む場合、波面を大きく乱す位相情報信号を波面変調部２１へ出力する。また、段階的に減少する波面収差の情報を目標収差信号に含む場合、その情報に対応する位相情報信号を波面変調部２１へ出力する。 The wavefront control unit 13 receives the target aberration signal from the control unit 11 and outputs a phase information signal of the light beam compensated by the wavefront modulation unit 21. Specifically, based on the information on the wavefront aberration included in the target aberration signal, a two-dimensional phase distribution of a cross section perpendicular to the optical axis of the light beam is calculated, and the information is output to the wavefront modulation unit 21 as a phase information signal. To do. That is, when information on large wavefront aberration that can be controlled by the wavefront modulation unit 21 is included in the target aberration signal, a phase information signal that greatly disturbs the wavefront is output to the wavefront modulation unit 21. When the target aberration signal includes wavefront aberration information that gradually decreases, a phase information signal corresponding to the information is output to the wavefront modulation unit 21.
波面変調部２１は、大気のゆらぎによる光ビームの波面の変動を補償する。更に、光ビームの瞬断が発生したとき、波面制御部１３からの位相情報信号に基づき、光制御装置１へ入射する光ビームの空間的な位相を変調し、出射する。つまり、光ビームの進行方向（波面変調部２１へ入射する方向）に交差する２次元面内の複数領域における光の位相を制御し、光増幅部３０へ光ビームを出射もしくは反射させる。なお、波面変調部２１には、可変形ミラー(Deformable Mirror)や、液晶パネルなどを用いることができる。具体的には、波面制御部１３から波面を大きく乱す位相情報信号が入力された場合、波面変調部２１は、その信号に基づき、光ビームに大きな波面収差を付与する。これにより、光ビームは波面が大きく乱れ、光増幅部３０へ出力する光ビームの割合が低下する。また、波面制御部１３から波面の乱れを段階的に減少する位相情報信号が入力された場合、その信号に基づき、光ビームが有する波面収差を段階的に低減する。これに伴い、光増幅部３０へ出力する光ビームの割合が段階的に増加する。 The wavefront modulation unit 21 compensates for fluctuations in the wavefront of the light beam due to atmospheric fluctuations. Further, when an instantaneous interruption of the light beam occurs, the spatial phase of the light beam incident on the light control device 1 is modulated and emitted based on the phase information signal from the wavefront control unit 13. That is, the phase of light in a plurality of regions in a two-dimensional plane intersecting the traveling direction of the light beam (the direction incident on the wavefront modulation unit 21) is controlled, and the light beam is emitted or reflected to the light amplification unit 30. The wavefront modulation unit 21 can be a deformable mirror, a liquid crystal panel, or the like. Specifically, when a phase information signal that greatly disturbs the wavefront is input from the wavefront control unit 13, the wavefront modulation unit 21 gives a large wavefront aberration to the light beam based on the signal. As a result, the wavefront of the light beam is greatly disturbed, and the ratio of the light beam output to the optical amplifying unit 30 is reduced. Further, when a phase information signal that reduces the wavefront disturbance stepwise is input from the wavefront control unit 13, the wavefront aberration of the light beam is reduced stepwise based on the signal. Accordingly, the ratio of the light beam output to the optical amplification unit 30 increases stepwise.
なお、大きく乱した波面を復元した後、光増幅部３０の光増幅を再開することにより、光増幅部３０へ入射された光ビームは増幅され、受光部３５は光ビームに含まれる通信信号を検出する。 In addition, after restoring the largely disturbed wavefront, the light amplification of the light amplifying unit 30 is resumed, whereby the light beam incident on the light amplifying unit 30 is amplified, and the light receiving unit 35 receives the communication signal included in the light beam. To detect.
次に、図２および図３を参照して、光制御装置１を用いた光制御方法について説明する。図２は光制御装置１を用いた光制御方法を説明するためのフローチャートであり、図３は目標収差信号（目標波面）と受光強度情報信号（強度情報）との関係を示す図である。なお、図３では、目標収差信号と受光強度情報信号との関係が直線的に変化する場合を示しているが、これに限るものではない。目標収差が大きくなることにより受光強度が低下する関係であれば良く、例えば、目標収差信号と受光強度情報信号との関係が曲線的に変化する場合であってもよい。 Next, a light control method using the light control device 1 will be described with reference to FIGS. 2 and 3. FIG. 2 is a flowchart for explaining a light control method using the light control device 1, and FIG. 3 is a diagram showing a relationship between a target aberration signal (target wavefront) and a received light intensity information signal (intensity information). FIG. 3 shows a case where the relationship between the target aberration signal and the received light intensity information signal changes linearly, but is not limited to this. Any relationship may be used as long as the target aberration increases and the received light intensity decreases. For example, the relationship between the target aberration signal and the received light intensity information signal may change in a curved line.
図２および図３を参照して、まず、制御部１１は検出部９から入力する受光強度情報信号が閾値以下であるかどうかを監視する（ステップＳ１）。閾値より大きい場合（ステップＳ１がＮｏの場合）、受光強度情報信号の監視を続ける。一方、閾値以下の場合（ステップＳ１がＹｅｓの場合）、制御部１１は波面収差を増大させる(大きな波面収差の情報を有する）目標収差信号を波面制御部１３へ出力する（ステップＳ２）。具体的には、図３に示すように、受光強度情報信号が閾値であるときの目標収差信号Ａ０より大きい値ＡＮを出力する。 Referring to FIGS. 2 and 3, first, control unit 11 monitors whether the received light intensity information signal input from detection unit 9 is equal to or less than a threshold value (step S1). When larger than the threshold value (when Step S1 is No), the monitoring of the received light intensity information signal is continued. On the other hand, if it is equal to or less than the threshold value (when Step S1 is Yes), the control unit 11 outputs a target aberration signal that increases wavefront aberration (having information on large wavefront aberration) to the wavefront control unit 13 (Step S2). Specifically, as shown in FIG. 3, a value A N larger than the target aberration signal A 0 when the received light intensity information signal is a threshold value is output.
次に、制御部１１は光の増幅を減少（停止あるいは低下）させる光増幅制御信号を光増幅部３０へ出力する（ステップＳ３）。続いて、制御部１１は波面収差を減少させる（波面収差を段階的に減少させる情報を有する）目標収差信号を波面制御部１３へ出力する（ステップＳ４）。このとき、波面制御部１３へ出力する目標収差信号の値はＡＮからＡ０との間の値ＡＮ－１である。その後、制御部１１は、検出部９から入力する受光強度情報信号が閾値以上であるかどうかを監視する（ステップＳ５）。閾値より小さい場合（ステップＳ５がＮｏの場合）、ステップＳ４へ戻る。この時、ステップＳ４では、制御部１１は、ＡＮ－１より小さくＡ０より大きい値ＡＮ－２を付与した目標収差信号を波面制御部１３へ出力する。このように、ＡＮから段階的にＡ０へ近づく値を付与した目標収差信号を波面制御部１３へ出力する。 Next, the control unit 11 outputs an optical amplification control signal for reducing (stopping or reducing) the amplification of light to the optical amplification unit 30 (step S3). Subsequently, the control unit 11 outputs a target aberration signal for reducing the wavefront aberration (having information for gradually reducing the wavefront aberration) to the wavefront control unit 13 (step S4). At this time, the value of the target aberration signal output to the wavefront control unit 13 is a value A N−1 between A N and A 0 . Thereafter, the control unit 11 monitors whether or not the received light intensity information signal input from the detection unit 9 is greater than or equal to a threshold value (step S5). When smaller than the threshold value (when Step S5 is No), the process returns to Step S4. At this time, in step S4, the control unit 11 outputs a target aberration signal to which the value A N−2 smaller than A N−1 and larger than A 0 is given to the wavefront control unit 13. In this way, the target aberration signal to which a value that gradually approaches A 0 from A N is output to the wavefront control unit 13.
なお、波面制御部１３は、目標収差信号に付与された情報ＡＮ、ＡＮ－１、ＡＮ－２が入力される毎に、この信号に基づいて作成した光ビームへ付与する位相分布の情報を波面変調部２１へ出力する。また、受光強度情報信号が閾値以上の場合（ステップＳ５がＹｅｓの場合）、制御部１１は、光の増幅を再開する、あるいは元の光の増幅量に戻す光増幅制御信号を光増幅部３へ出力する（ステップＳ６）。
なお、制御部１１のステップＳ１からステップＳ５までの動作時間は、光ビームが瞬断している時間より長くなるように設定する。 Each time the information A N , A N-1 , A N-2 given to the target aberration signal is input, the wavefront controller 13 determines the phase distribution to be given to the light beam created based on this signal. Information is output to the wavefront modulation unit 21. When the received light intensity information signal is equal to or greater than the threshold (when Step S5 is Yes), the control unit 11 resumes the light amplification or returns the light amplification control signal to the original light amplification amount to the light amplification unit 3. (Step S6).
Note that the operation time from step S1 to step S5 of the control unit 11 is set to be longer than the time during which the light beam is momentarily interrupted.
以上のように、本発明の第１の実施形態では、受光強度情報信号が閾値以下となることに伴い、大気のゆらぎに伴う光ビームの波面補償を行う波面変調部２１から光増幅部３０へ入力する光ビームを低下させる。これとともに、光増幅部３０の光ビームの増幅を停止あるいは低減させる。また、受光強度情報信号が閾値以上となるまで、段階的に波面収差を変化させることにより、波面変調部２１から光増幅部３０へ入力する光ビームを増加させた後、光増幅部３０の光ビームの増幅を復帰させる。これにより、光サージの抑制のために新たな光学素子を必要とせず、組立作業を含めたコスト増大を抑制しつつ、制御の複雑化を抑えることができる。 As described above, in the first embodiment of the present invention, from the wavefront modulation unit 21 that performs wavefront compensation of the light beam accompanying the fluctuation of the atmosphere to the optical amplification unit 30 as the received light intensity information signal becomes less than the threshold value. Decreasing the input light beam. At the same time, the amplification of the light beam of the light amplifying unit 30 is stopped or reduced. Further, by increasing the light beam input from the wavefront modulation unit 21 to the optical amplification unit 30 by changing the wavefront aberration in a stepwise manner until the received light intensity information signal becomes equal to or greater than the threshold value, the light of the optical amplification unit 30 is increased. Restore beam amplification. Thereby, a new optical element is not required for suppression of the optical surge, and control complexity can be suppressed while suppressing an increase in cost including assembly work.
また、波面変調部２１に入力する光ビームが瞬断しても、光増幅部３０に生じる光サージの発生を抑制することができる。光ビームの瞬断が回復したときは、波面変調部２１から光増幅部３０への光ビームが効率的に入力するとともに、光増幅部３０の光の増幅も回復するため、光通信時の受光感度の低下を防止することができる。 Further, even if the light beam input to the wavefront modulation unit 21 is momentarily interrupted, it is possible to suppress the occurrence of an optical surge generated in the optical amplification unit 30. When the instantaneous interruption of the light beam is recovered, the light beam is efficiently input from the wavefront modulation unit 21 to the optical amplification unit 30 and the light amplification of the optical amplification unit 30 is also recovered. A decrease in sensitivity can be prevented.
〔第２の実施形態〕続いて、本発明の第２の実施形態について詳細に説明する。図４は本発明の第２の実施形態である光制御装置２の構成を示すブロック図である。 [Second Embodiment] Next, the second embodiment of the present invention will be described in detail. FIG. 4 is a block diagram showing the configuration of the light control apparatus 2 according to the second embodiment of the present invention.
図４を参照して、第２の実施形態の光制御装置２は、第１の実施形態の構成に加え、波面演算部１４と光分割部２２と光集光部３１と光ファイバ３２と光ファイバアンプ３３と励起光源３４と受光部３５とを備える。また、第１の実施形態の検出部９を構成する光強度演算部１０と波面センサ２３とを備え、第１の実施形態の波面制御部１３を構成する目標波面演算部１２と波面演算部１４とを備える。 Referring to FIG. 4, the light control apparatus 2 according to the second embodiment includes a wavefront calculation unit 14, a light dividing unit 22, a light condensing unit 31, an optical fiber 32, and light in addition to the configuration of the first embodiment. A fiber amplifier 33, an excitation light source 34, and a light receiving unit 35 are provided. Moreover, the light intensity calculating part 10 and the wavefront sensor 23 which comprise the detection part 9 of 1st Embodiment are provided, the target wavefront calculating part 12 and the wavefront calculating part 14 which comprise the wavefront control part 13 of 1st Embodiment. With.
光分割部２２は、位相の変調を受けた光ビームを２つの光路に分割する。つまり、波面センサ２３へ向う光路と光集光部３１へ向う光路とに分割する。このようなデバイスとしては、ハーフミラー、プリズム、偏光ビームスプリッタを用いることができる。なお、分割された各光路の強度比は等しいとは限らない。 The light splitting unit 22 splits the light beam subjected to phase modulation into two optical paths. In other words, the optical path toward the wavefront sensor 23 and the optical path toward the light condensing unit 31 are divided. As such a device, a half mirror, a prism, or a polarization beam splitter can be used. Note that the intensity ratios of the divided optical paths are not necessarily equal.
波面センサ２３は、検出部として例えばＣＣＤ（Ｃｈａｒｇｅ　Ｃｏｕｐｌｅｄ　Ｄｅｖｉｃｅ）素子、ＣＭＯＳ（Ｃｏｍｐｌｅｍｅｎｔａｒｙ　Ｍｅｔａｌ　Ｏｘｉｄｅ　Ｓｅｍｉｃｏｎｄｕｃｔｏｒ）素子などのカメラ部を備えている。そして、光分割部２２により分割された一方の光ビームの空間的な位相分布を測定し、位相分布の情報を電気信号に変換して出力する。具体的には、光ビームの進行方向（波面センサ２３へ入射する方向）に交差する２次元面内の、複数領域における位相あるいは位相の傾きの情報である位相情報を電気信号に変換して波面演算部１４へ出力する。 The wavefront sensor 23 includes a camera unit such as a CCD (Charge Coupled Device) element or a CMOS (Complementary Metal Oxide Semiconductor) element as a detection unit. Then, the spatial phase distribution of one of the light beams divided by the light dividing unit 22 is measured, and information on the phase distribution is converted into an electrical signal and output. Specifically, the phase information that is information on the phase or the gradient of the phase in a plurality of regions in a two-dimensional plane intersecting the traveling direction of the light beam (the direction of incidence on the wavefront sensor 23) is converted into an electric signal to generate a wavefront. The result is output to the calculation unit 14.
また、波面センサ２３は入射した光ビームの空間的な強度分布を測定（あるいは検出）し、強度分布の情報を電気信号に変換して出力する。具体的には、光ビームの進行方向（波面センサ２３へ入射する方向）に交差する２次元面内の複数領域における強度あるいは強度の傾きの情報を電気信号に変換して光強度演算部１０へ出力する。以上のような波面センサ２３には、シャック・ハルトマン式波面センサ、波面曲率センサなどを用いることができる。 The wavefront sensor 23 measures (or detects) the spatial intensity distribution of the incident light beam, converts the intensity distribution information into an electrical signal, and outputs it. Specifically, information on the intensity or gradient of intensity in a plurality of regions in a two-dimensional plane intersecting the traveling direction of the light beam (the direction of incidence on the wavefront sensor 23) is converted into an electrical signal and sent to the light intensity calculation unit 10. Output. As the wavefront sensor 23 as described above, a Shack-Hartmann wavefront sensor, a wavefront curvature sensor, or the like can be used.
光強度演算部１０は、波面センサ２３が測定（あるいは検出）した２次元面内の強度あるいは強度の傾きの情報に関わる電気信号から受光強度（強度情報）を演算し、演算した情報の電気信号を受光強度情報信号として制御部１１へ出力する。なお、受光強度情報信号は受光強度の変化に応じて変化する信号である。 The light intensity calculation unit 10 calculates the received light intensity (intensity information) from the electric signal related to the intensity or intensity gradient information in the two-dimensional plane measured (or detected) by the wavefront sensor 23, and the calculated electric signal of the information Is output to the control unit 11 as a received light intensity information signal. The received light intensity information signal is a signal that changes in accordance with a change in received light intensity.
波面演算部１４は、波面センサ２３が出力した位相あるいは位相の傾きの情報（位相情報）に関する電気信号から光ビームの波面を演算し、演算した情報の電気信号を波面補償演算部１５へ出力する。上述した波面センサ２３としてシャック・ハルトマン式波面センサ、波面曲率センサを用いる場合、波面補償演算部１５へ出力する電気信号は、波面センサ２３へ入射した光ビームの２次元の位相情報に対応した信号である。 The wavefront calculation unit 14 calculates the wavefront of the light beam from the electrical signal related to the phase or phase slope information (phase information) output from the wavefront sensor 23, and outputs the calculated electrical signal to the wavefront compensation calculation unit 15. . When a Shack-Hartmann wavefront sensor or wavefront curvature sensor is used as the wavefront sensor 23 described above, the electrical signal output to the wavefront compensation calculation unit 15 is a signal corresponding to the two-dimensional phase information of the light beam incident on the wavefront sensor 23. It is.
制御部１１は受光強度情報信号に基づいて、波面変調部２１が光ビームの位相に付与する目標収差信号を設定し、目標波面演算部１２へ出力する。また、目標波面演算部１２は入力した目標収差信号に基づいて、目標収差に対応する２次元の位相分布の情報を含む位相情報信号を出力する。目標収差によって、後述する光集光部３１が光ファイバ３２のコア上に形成される集光スポットを変化させる。具体的には、光ファイバ３２の入射面の集光スポットの形状、大きさ、位置を変えるように目標収差信号を設定し、また、光ファイバ３２の入射面上のコア径の中に導くよう集光スポットの形状、大きさ、位置を段階的にかえるように目標収差信号を設定する。 Based on the received light intensity information signal, the control unit 11 sets a target aberration signal that the wavefront modulation unit 21 gives to the phase of the light beam, and outputs the target aberration signal to the target wavefront calculation unit 12. Further, the target wavefront calculator 12 outputs a phase information signal including information on a two-dimensional phase distribution corresponding to the target aberration based on the input target aberration signal. Depending on the target aberration, a light condensing unit 31 to be described later changes a condensing spot formed on the core of the optical fiber 32. Specifically, the target aberration signal is set so as to change the shape, size, and position of the condensing spot on the incident surface of the optical fiber 32, and is guided into the core diameter on the incident surface of the optical fiber 32. The target aberration signal is set so as to change the shape, size, and position of the focused spot in stages.
波面補償演算部１５は、目標波面演算部１２より入力される位相情報信号と、波面演算部１４より入力される光ビームの波面の演算情報に関する電気信号との差分を算出し、その情報から演算した波面変調部２１の制御信号を出力する。具体的には、光ビームの目標とする波面に関する位相情報と波面センサ２３で測定した光ビームの波面に関する位相情報との差分が小さくなるように波面変調部２１をフィードバック制御する。これによって、波面変調部２１から出射する光ビームの波面を所望の光ビームの波面へと変更する。ただし、波面情報は２次元の行列であり、また波面変調部２１の制御信号も２次元の行列であることから、波面補償演算部での演算は変換行列を含む行列演算となる。 The wavefront compensation calculation unit 15 calculates the difference between the phase information signal input from the target wavefront calculation unit 12 and the electrical signal related to the calculation information of the wavefront of the light beam input from the wavefront calculation unit 14, and calculates from the information The control signal of the wavefront modulation unit 21 is output. Specifically, the wavefront modulation unit 21 is feedback-controlled so that the difference between the phase information related to the target wavefront of the light beam and the phase information related to the wavefront of the light beam measured by the wavefront sensor 23 becomes small. As a result, the wavefront of the light beam emitted from the wavefront modulation unit 21 is changed to the wavefront of the desired light beam. However, since the wavefront information is a two-dimensional matrix and the control signal of the wavefront modulation unit 21 is also a two-dimensional matrix, the calculation in the wavefront compensation calculation unit is a matrix calculation including a conversion matrix.
光集光部３１は、光分割部２２により分割された光ビームのうち、光ファイバ３２の方向へ進む光ビームを集光し、集光した光ビームは光ファイバ３２のコア部に入射する。光ファイバ上の集光スポット径が光ファイバのコア径に近く、理想的にはコア径に等しくなる場合、所望の光通信の性能を達成できる。 The light condensing unit 31 condenses the light beam traveling in the direction of the optical fiber 32 among the light beams divided by the light dividing unit 22, and the collected light beam enters the core of the optical fiber 32. When the focused spot diameter on the optical fiber is close to the core diameter of the optical fiber and ideally equal to the core diameter, the desired optical communication performance can be achieved.
光ファイバ３２は、光ファイバアンプ３３に接続している。光ファイバアンプ３３は、光空間通信の通信信号の受光感度を向上させる光学素子であり、光ファイバ３２へ入射し導光した光ビームの強度を励起光源３４から注入された励起光に応じて変化させ、受光部３５へ出射する。具体的には、励起光源３４からの励起光が光ファイバアンプへ注入される場合、光ファイバ３２から入射した光ビームは増幅され受光部３５へ出射する。また、励起光が光ファイバアンプへ注入されない場合、光ファイバ３２から入射した光ビームは増幅されることなく受光部へ出射する。 The optical fiber 32 is connected to the optical fiber amplifier 33. The optical fiber amplifier 33 is an optical element that improves the light receiving sensitivity of the communication signal of the optical space communication, and changes the intensity of the light beam incident and guided to the optical fiber 32 according to the excitation light injected from the excitation light source 34. And output to the light receiving unit 35. Specifically, when the excitation light from the excitation light source 34 is injected into the optical fiber amplifier, the light beam incident from the optical fiber 32 is amplified and emitted to the light receiving unit 35. When the excitation light is not injected into the optical fiber amplifier, the light beam incident from the optical fiber 32 is emitted to the light receiving unit without being amplified.
受光部３５は、フォトダイオードなどの光電変換素子であり、光ファイバアンプ３３からの入射した光ビームを電気信号に変換し、受信信号として後段の回路に出力する。 The light receiving unit 35 is a photoelectric conversion element such as a photodiode, converts the incident light beam from the optical fiber amplifier 33 into an electrical signal, and outputs it as a received signal to a subsequent circuit.
以上説明した光制御装置２では、波面変調部２１によって光ビームに収差を加えて波面を乱した場合、波面センサ２３が検出する受光強度情報信号が低下する。それと共に、光ファイバ３２の入射面上のコアに対する集光ビームの大きさ、形状、または、位置が変化、または移動し、光ファイバへ入射する光ビームの結合効率が低下する。また、波面変調部２１によって光ビームの乱れた波面を段階的に補償すると、波面センサ２３が検出する受光強度情報信号が段階的に増加する。それと共に、光ファイバ３２の入射面上のコアの径、位置に集光ビームの大きさ、形状、または、位置が変化または移動し、光ファイバ３２へ入射する光ビームの結合効率が改善する。 In the light control device 2 described above, when the wavefront modulator 21 adds aberration to the light beam and disturbs the wavefront, the received light intensity information signal detected by the wavefront sensor 23 decreases. At the same time, the size, shape, or position of the focused beam with respect to the core on the incident surface of the optical fiber 32 changes or moves, and the coupling efficiency of the light beam incident on the optical fiber decreases. Further, when the wavefront where the light beam is disturbed is compensated stepwise by the wavefront modulator 21, the received light intensity information signal detected by the wavefront sensor 23 is increased stepwise. At the same time, the size, shape, or position of the focused beam is changed or moved to the diameter and position of the core on the incident surface of the optical fiber 32, and the coupling efficiency of the light beam incident on the optical fiber 32 is improved.
このように、第２の実施形態の光制御装置２は、第１の実施形態と同様に、入射する光ビームの波面の歪、または波面の時間的なゆらぎがあったとしても、波面変調部２１によって光ビームの波面を補償し、光ファイバ３２へ入射する光ビームの結合効率を維持する。これにより、光通信時の受光感度の低下を抑制し、所望の通信性能を達成することができる。 As described above, the light control device 2 according to the second embodiment is similar to the first embodiment in that the wavefront modulation unit can be used even if there is a wavefront distortion or wavefront fluctuation of the incident light beam. The wavefront of the light beam is compensated by 21 and the coupling efficiency of the light beam incident on the optical fiber 32 is maintained. Thereby, the fall of the light reception sensitivity at the time of optical communication can be suppressed, and desired communication performance can be achieved.
次に、図５および図６を参照して、光制御装置２を用いた光抑制方法について説明する。図５は光制御装置２の動作を説明するためのフローチャートであり、図６は目標収差信号と受光強度情報信号との関係を示す図である。図６に示すように、球面収差に基づいた目標収差信号の増加に伴い受光強度情報信号が減少し、球面収差に基づいた目標収差信号の減少に伴い受光強度情報信号は増加する。なお、図６では、目標収差信号を球面収差とした場合を示したが、これに限るものではなく、コマ収差や非点収差など他の収差であっても良い。あるいは、波面をゼルニケ多項式で展開したときの任意の係数に対応する波面であっても良く、それらを複合した波面の組合せであっても良い。 Next, a light suppression method using the light control device 2 will be described with reference to FIGS. FIG. 5 is a flowchart for explaining the operation of the light control device 2, and FIG. 6 is a diagram showing the relationship between the target aberration signal and the received light intensity information signal. As shown in FIG. 6, the received light intensity information signal decreases as the target aberration signal based on spherical aberration increases, and the received light intensity information signal increases as the target aberration signal decreases based on spherical aberration. Although FIG. 6 shows the case where the target aberration signal is spherical aberration, the present invention is not limited to this, and other aberrations such as coma and astigmatism may be used. Alternatively, it may be a wavefront corresponding to an arbitrary coefficient when the wavefront is expanded by a Zernike polynomial, or may be a combination of wavefronts combining them.
図５および図６を参照して、光空間通信中に、制御部１１は、波面センサ２３が測定した受光強度に基づく光強度演算部１０からの受光強度情報信号（強度情報）が閾値以下であるかどうかを監視する（ステップＳ１１）。受光強度情報信号が閾値より大きい場合（ステップＳ１がＮｏの場合）、受光強度情報信号の監視を続ける。一方、受光強度情報信号が閾値以下の場合（ステップＳ１がＹｅｓの場合）、制御部１１は球面収差を増大させる（大きな球面収差の情報を有する）目標収差信号を目標波面演算部１２へ出力する（ステップＳ１２）。具体的には、図６に示すように、受光強度情報信号が閾値であるときの目標収差信号の波面収差の情報Ｂ０より大きい値ＢＮを出力する。次に、制御部１１は光の増幅を減少（停止あるいは低下）させる光増幅制御信号を励起光源３４へ出力する（ステップＳ１３）。 Referring to FIGS. 5 and 6, during the optical space communication, the control unit 11 has a light reception intensity information signal (intensity information) from the light intensity calculation unit 10 based on the light reception intensity measured by the wavefront sensor 23 equal to or less than a threshold value. Whether or not there is is monitored (step S11). When the received light intensity information signal is larger than the threshold (when Step S1 is No), the received light intensity information signal is continuously monitored. On the other hand, when the received light intensity information signal is equal to or smaller than the threshold value (when Step S1 is Yes), the control unit 11 outputs a target aberration signal that increases spherical aberration (having information on large spherical aberration) to the target wavefront calculation unit 12. (Step S12). Specifically, as shown in FIG. 6, a value B N greater than the wavefront aberration information B 0 of the target aberration signal when the received light intensity information signal is a threshold value is output. Next, the control unit 11 outputs an optical amplification control signal for reducing (stopping or reducing) the light amplification to the excitation light source 34 (step S13).
続いて、制御部１１は、球面収差を減少させる（球面収差を段階的に減少させる情報を有する）目標収差信号を目標波面演算部１２へ出力する（ステップＳ１４）。このとき、目標波面演算部１２へ出力する目標収差信号の値はＢＮからＢ０との間の値ＢＮ－１である。その後、制御部１１は、光強度演算部１０から入力する受光強度情報信号が閾値以上であるかどうかを監視する（ステップＳ１５）。言い換えると、光ファイバ３２へ集光する光ビームの結合効率が所定の閾値以上であるかを監視する。受光強度情報信号が閾値より小さい場合（ステップＳ１５がＮｏの場合）、つまり、光ビームの結合効率が閾値より小さい場合、ステップＳ１４へ戻る。この時、ステップＳ１４では、制御部１１がＢＮ－１より小さくＢ０より大きい値ＢＮ－２を付与した目標収差信号を目標波面演算部１２へ出力する。このように、ＢＮから段階的にＢ０へ近づく値を付与した目標収差信号を目標波面演算部１２へ出力する。なお、目標波面演算部１２は、目標収差信号に付与された情報ＢＮ、ＢＮ－１、ＢＮ－２が入力される毎に、この信号に基づいて作成した光ビームへ付与する位相分布の情報を波面補償演算部１５へ出力する。そして、波面補償演算部１５は、目標波面演算部１２からの目標収差信号と、波面演算部１４からの光ビームの波面の関する電気信号との差分を算出し、その情報から演算した波面変調部２１の制御信号を出力する。 Subsequently, the control unit 11 outputs a target aberration signal for reducing the spherical aberration (having information for gradually reducing the spherical aberration) to the target wavefront calculation unit 12 (step S14). At this time, the value of the target aberration signal output to the target wavefront calculator 12 is a value B N−1 between B N and B 0 . Thereafter, the controller 11 monitors whether or not the received light intensity information signal input from the light intensity calculator 10 is equal to or greater than a threshold (step S15). In other words, it is monitored whether the coupling efficiency of the light beam focused on the optical fiber 32 is equal to or higher than a predetermined threshold value. When the received light intensity information signal is smaller than the threshold value (when Step S15 is No), that is, when the light beam coupling efficiency is smaller than the threshold value, the process returns to Step S14. At this time, in step S14, the control unit 11 outputs the target aberration signal to which the value B N−2 smaller than B N−1 and larger than B 0 is given to the target wavefront calculation unit 12. Thus, it outputs the target aberration signal imparted with stepwise values approaching to B 0 from B N to the target wavefront computation section 12. The target wavefront computing unit 12 applies the phase distribution to the light beam created based on this signal every time the information B N , B N-1 , B N-2 added to the target aberration signal is input. Is output to the wavefront compensation calculation unit 15. Then, the wavefront compensation calculation unit 15 calculates the difference between the target aberration signal from the target wavefront calculation unit 12 and the electric signal related to the wavefront of the light beam from the wavefront calculation unit 14, and calculates the wavefront modulation unit calculated from the information 21 control signals are output.
また、受光強度情報信号が閾値以上の場合（ステップＳ１５がＹｅｓの場合）、つまり、光ビームの結合効率が閾値以上の場合、制御部１１は、光の増幅を再開あるいは元の状態に戻す、つまり、励起光の出射を回復させる光増幅制御信号を励起光源３４へ出力する（ステップＳ１６）。その後、光空間通信が再開される。 When the received light intensity information signal is equal to or greater than the threshold value (when Step S15 is Yes), that is, when the light beam coupling efficiency is equal to or greater than the threshold value, the control unit 11 resumes or restores the light amplification. That is, an optical amplification control signal for recovering the emission of the excitation light is output to the excitation light source 34 (step S16). Thereafter, optical space communication is resumed.
以上のように、本発明の第２の実施形態では、受光強度情報信号が閾値以下となることに伴い、波面変調部２１により光ビームに収差を加えて波面を乱すことにより、光ファイバ３２への光ビームの結合効率を低下させる。これとともに、励起光源３４への励起光の出射を停止あるいは低減させる。また、受光強度情報信号が閾値以上となるまで、波面変調部２１による乱れた波面を段階的に改善させた後、励起光源３４への励起光の出射を再開させる。この動作は、大気のゆらぎに伴う光ビームの波面補償を行う波面補償する構成部品、および、受光感度を向上させる光増幅する構成部品により実現している。したがって、光空間通信時の受光感度を向上させつつ、光サージを抑制するための構成部品の追加、その追加に伴う組立作業の工数増加、追加された構成部品の制御ステップの追加を抑えることができる。 As described above, in the second embodiment of the present invention, as the received light intensity information signal becomes equal to or lower than the threshold value, the wavefront modulation unit 21 adds aberration to the light beam and disturbs the wavefront, thereby shifting to the optical fiber 32. This reduces the coupling efficiency of the light beam. At the same time, the emission of the excitation light to the excitation light source 34 is stopped or reduced. Further, after improving the distorted wavefront by the wavefront modulation unit 21 stepwise until the received light intensity information signal becomes equal to or greater than the threshold value, the emission of the excitation light to the excitation light source 34 is resumed. This operation is realized by a component for wavefront compensation that performs wavefront compensation of a light beam caused by atmospheric fluctuations and a component for optical amplification that improves the light receiving sensitivity. Therefore, while improving the light receiving sensitivity during optical space communication, it is possible to suppress the addition of components for suppressing optical surges, the increase in man-hours for assembly work accompanying the addition, and the addition of control steps for the added components it can.
さらに、波面変調部２１に入射する光ビームが瞬断されても、励起光が光ファイバアンプ３３に蓄積されエネルギーが光サージとして受光部３５へ出力することを防止できる。さらに、光ビームの波面乱れが回復したとき、光ファイバ３２へ集光する光ビームが効率的に入射するとともに、励起光源３４の励起光の出射を再開するため、光通信時の受光感度が低下することはない。 Furthermore, even if the light beam incident on the wavefront modulation unit 21 is momentarily interrupted, it is possible to prevent the excitation light from being accumulated in the optical fiber amplifier 33 and the energy from being output to the light receiving unit 35 as an optical surge. Further, when the wave front disturbance of the light beam is recovered, the light beam focused on the optical fiber 32 is efficiently incident and the emission of the excitation light from the excitation light source 34 is resumed, so that the light receiving sensitivity during optical communication is reduced. Never do.
なお、第２の実施形態では、球面収差を徐々に改善し、受光強度情報信号が閾値以上となった後に再開させる光増幅制御信号を励起光源３４へ出力したが、これに限るものではない。例えば、球研収差を徐々に改善すると共に、励起光を徐々に増幅させる光増幅制御信号を励起光源３４へ出力してもよい。 In the second embodiment, the spherical aberration is gradually improved and the light amplification control signal to be restarted after the received light intensity information signal becomes equal to or higher than the threshold value is output to the excitation light source 34. However, the present invention is not limited to this. For example, an optical amplification control signal for gradually improving the spherical aberration and gradually amplifying the excitation light may be output to the excitation light source 34.
〔第３の実施形態〕続いて、本発明の第３の実施形態について詳細に説明する。図７は本発明の第３の実施形態である光制御装置３の構成を示すブロック図である。第３の実施形態の光制御装置３は、第２の実施形態の光制御装置２に保護時間タイマ１６が追加された構成であり、第３の実施形態の制御部１１は第２の実施形態の制御部１１に機能を追加している。それ以外の構成部品は第２の実施形態の光制御装置２と同じであり、それらの説明は省略する。 [Third Embodiment] Next, a third embodiment of the present invention will be described in detail. FIG. 7 is a block diagram showing the configuration of the light control apparatus 3 according to the third embodiment of the present invention. The light control device 3 of the third embodiment has a configuration in which a protection time timer 16 is added to the light control device 2 of the second embodiment, and the control unit 11 of the third embodiment is the second embodiment. A function is added to the control unit 11. Other components are the same as those of the light control device 2 of the second embodiment, and a description thereof will be omitted.
図７を参照して、制御部１１は、光強度演算部１０からの受光強度情報信号に基づき目標収差信号および光増幅制御信号を出力する。これとともに、保護時間タイマ１６へ保護時間の開始情報を含む起動信号を出力し、保護時間タイマ１６から保護時間の終了情報を含む終了信号を入力する。なお、保護時間は、光増幅制御信号によって励起光源３４による光の増幅を停止あるいは低下させた時刻から光ファイバアンプ３３に蓄積された励起光のエネルギーが自然放出される時刻までの時間である。また、この保護時間の間、増加した目標波面の収差を維持し、段階的に減少させることは行わない。 Referring to FIG. 7, control unit 11 outputs a target aberration signal and an optical amplification control signal based on the received light intensity information signal from light intensity calculation unit 10. At the same time, a start signal including protection time start information is output to the protection time timer 16, and an end signal including protection time end information is input from the protection time timer 16. The protection time is the time from the time when the amplification of light by the excitation light source 34 is stopped or reduced by the optical amplification control signal to the time when the energy of the excitation light accumulated in the optical fiber amplifier 33 is spontaneously emitted. In addition, during this protection time, the increased target wavefront aberration is maintained and is not reduced stepwise.
保護時間タイマ１６は、制御部１１からの起動信号を入力し、その信号によってタイマを起動する。タイマが起動後、所定の保護時間に到達した後、保護時間の終了の情報を含む終了信号を出力する。 The protection time timer 16 receives an activation signal from the control unit 11 and activates the timer according to the signal. After reaching the predetermined protection time after the timer is started, an end signal including information on the end of the protection time is output.
次に、図８および図６を参照して、光制御装置３を用いた光抑制方法について説明する。図８は光制御装置３の動作を説明するためのフローチャートである。また、第３の実施形態の光制御装置３のフローチャートは、第２の実施形態の光制御装置２のフローチャートに保護時間タイマ起動、および、完了のフローを追加している。それ以外のフローは第２の実施形態の光制御装置３のフローと同じであり、それらの説明は省略する。また、第２の実施形態の動作と同じように、目標収差信号は球面収差に基づき設定される信号としている。 Next, a light suppression method using the light control device 3 will be described with reference to FIGS. FIG. 8 is a flowchart for explaining the operation of the light control device 3. Further, in the flowchart of the light control device 3 of the third embodiment, a protection time timer activation and completion flow are added to the flowchart of the light control device 2 of the second embodiment. The other flow is the same as the flow of the light control device 3 of the second embodiment, and a description thereof will be omitted. As in the operation of the second embodiment, the target aberration signal is a signal set based on spherical aberration.
図８および図６を参照して、光空間通信中に、制御部１１は、ステップＳ１１からステップＳ１３までのフローを実施する。続いて、制御部１１は、保護時間タイマ１６へ保護時間の開始情報を含む起動信号を出力する（ステップＳ２０）。次に、制御部１１は、保護時間の終了情報を含む終了信号の入力の有無を監視する（ステップ２１）。終了信号の入力が無い場合（ステップ２１がＮｏの場合）、終了信号の入力の監視を続ける。一方、終了信号の入力が有る場合（ステップ２１がＹｅｓの場合）、次のステップへ進む。以降は、ステップＳ１４からステップＳ１６までのフローを実行する。 With reference to FIG. 8 and FIG. 6, the control part 11 implements the flow from step S11 to step S13 during optical space communication. Then, the control part 11 outputs the starting signal containing the start information of protection time to the protection time timer 16 (step S20). Next, the control unit 11 monitors whether or not an end signal including end information of the protection time is input (step 21). If there is no input of the end signal (No in step 21), the monitoring of the input of the end signal is continued. On the other hand, when there is an input of an end signal (when step 21 is Yes), the process proceeds to the next step. Thereafter, the flow from step S14 to step S16 is executed.
以上のように、本発明の第３の実施形態では、保護時間タイマ１６を設けることにより、保護時間の間、励起光の入力を抑制しつつ光ファイバアンプ３３に蓄積されたエネルギーが自然放出することができる。このため、第１の実施形態、および、第２の実施形態に比べてより安定に光サージの発生を抑制できる。 As described above, in the third embodiment of the present invention, by providing the protection time timer 16, the energy accumulated in the optical fiber amplifier 33 is spontaneously released while suppressing the input of excitation light during the protection time. be able to. For this reason, generation | occurrence | production of an optical surge can be suppressed more stably compared with 1st Embodiment and 2nd Embodiment.
なお、第３の実施形態では、制御部１１へ終了信号が入力されたとき、目標収差信号の値を段階的に小さくする（球面収差を段階的に小さくする）ように変化させたが、これに限るものではない。例えば、目標収差信号の大きな値から小さな値へ一度に変化させてもよい。ここで、目標収差信号の小さな値は、受光強度情報信号の閾値を下回る前の値であってもよい。 In the third embodiment, when the end signal is input to the control unit 11, the value of the target aberration signal is changed in a stepwise manner (spherical aberration is reduced in a stepwise manner). It is not limited to. For example, the target aberration signal may be changed from a large value to a small value at a time. Here, the small value of the target aberration signal may be a value before it falls below the threshold value of the received light intensity information signal.
〔第４の実施形態〕続いて、本発明の第４の実施形態について詳細に説明する。図９は本発明の第４の実施形態である光制御装置４の構成を示すブロック図である。第４の実施形態の光制御装置４は、第２の実施形態の光制御装置２に波面記憶部１７が追加された構成であり、第４の実施形態の制御部１１は第２の実施形態の制御部１１に機能を追加している。それ以外の構成部品は第２の実施形態の光制御装置２と同じであり、それらの説明は省略する。 [Fourth Embodiment] Next, a fourth embodiment of the present invention will be described in detail. FIG. 9 is a block diagram showing the configuration of the light control device 4 according to the fourth embodiment of the present invention. The light control device 4 of the fourth embodiment has a configuration in which a wavefront storage unit 17 is added to the light control device 2 of the second embodiment, and the control unit 11 of the fourth embodiment is the second embodiment. A function is added to the control unit 11. Other components are the same as those of the light control device 2 of the second embodiment, and a description thereof will be omitted.
図９を参照して、波面記録部１７は、受光部３５で検出された光強度信号と波面演算部１４で演算された波面の情報とを、光強度信号が低下した瞬間の波面として記憶する。具体的には、波面センサ２３の受光強度情報信号が低下した場合の波面、つまり、光ファイバ３２への光ビームの結合効率が低い場合において、増加あるいは減少する光強度信号の値ごとに、その値と対応する波面の情報とを記憶する。また、記憶した波面の情報を制御部１１へ目標波面情報として出力する。 Referring to FIG. 9, the wavefront recording unit 17 stores the light intensity signal detected by the light receiving unit 35 and the wavefront information calculated by the wavefront calculating unit 14 as the wavefront at the moment when the light intensity signal is reduced. . Specifically, when the light intensity information signal of the wavefront sensor 23 decreases, that is, when the coupling efficiency of the light beam to the optical fiber 32 is low, for each value of the light intensity signal that increases or decreases, The value and the corresponding wavefront information are stored. The stored wavefront information is output to the control unit 11 as target wavefront information.
波面センサ２３の受光強度情報信号が低下した場合の波面、つまり、光ファイバ３２への光ビームの結合効率が低い場合における波面演算部１４で演算された波面の情報は、光空間通信中に波面演算部１４を用いて光ビームの波面補償を行っている間に記憶してもよい。但し、これに限るものではない。波面演算部１４を用いた光ビームの波面補償を行わず受光部３５で検出される光強度信号の変動が大きい場合、波面演算部１４で演算された波面の情報を記憶してもよい。 The wavefront when the received light intensity information signal of the wavefront sensor 23 is lowered, that is, the wavefront information calculated by the wavefront calculator 14 when the coupling efficiency of the light beam to the optical fiber 32 is low, is the wavefront during optical space communication. You may memorize | store, while performing the wavefront compensation of a light beam using the calculating part 14. FIG. However, the present invention is not limited to this. When the fluctuation of the light intensity signal detected by the light receiving unit 35 is large without performing wavefront compensation of the light beam using the wavefront calculating unit 14, information on the wavefront calculated by the wavefront calculating unit 14 may be stored.
制御部１１は、光強度演算部１０からの受光強度情報信号と、波面記憶部１７からの波面の情報とを入力する。また、入力した受光強度情報信号に含まれる受光強度の低下を検出すると、つまり、受光部３５からの光強度信号の低下を検出すると、波面記憶部１７から入力された波面の情報を目標収差信号として目標波面演算部１２へ出力する。さらに、光の増幅を停止する光増幅制御信号を光増幅部３０へと出力する。 The control unit 11 inputs the received light intensity information signal from the light intensity calculation unit 10 and the wavefront information from the wavefront storage unit 17. When a decrease in received light intensity included in the input received light intensity information signal is detected, that is, when a decrease in light intensity signal from the light receiving unit 35 is detected, the wavefront information input from the wavefront storage unit 17 is used as the target aberration signal. To the target wavefront calculation unit 12. Further, an optical amplification control signal for stopping the amplification of light is output to the optical amplification unit 30.
次に、光制御装置４を用いた光制御方法について説明する。この制御方法では、光制御装置２の光制御方法のステップＳ１２、ステップＳ１４において、球面収差を改悪する、または、改善する目標収差信号として、波面記憶部１７から入力された波面の情報を用いる。それ以外のフローは光制御装置２を用いた光制御方法と同じである。 Next, a light control method using the light control device 4 will be described. In this control method, in step S12 and step S14 of the light control method of the light control apparatus 2, the wavefront information input from the wavefront storage unit 17 is used as a target aberration signal for improving or improving the spherical aberration. The other flow is the same as the light control method using the light control device 2.
このように、本発明の第４の実施形態では、光サージの影響を受ける受光部３５で検出した光強度信号に基づいて、波面センサ２３の受光強度情報信号が低下した場合の波面、つまり、光ファイバ３２への光ビームの結合効率が低い場合の波面の情報を目標収差として設定することができる。これにより、第１の実施形態、および、第２の実施形態に比べて、光サージによる影響を一層抑制することができる。 Thus, in the fourth embodiment of the present invention, the wavefront when the light reception intensity information signal of the wavefront sensor 23 is lowered based on the light intensity signal detected by the light receiving unit 35 affected by the light surge, that is, Wavefront information when the coupling efficiency of the light beam to the optical fiber 32 is low can be set as the target aberration. Thereby, compared with 1st Embodiment and 2nd Embodiment, the influence by an optical surge can be suppressed further.
また、第２の実施形態から第４の実施形態では、波面変調部２１の前段に捕捉追尾部を設けてもよい。すなわち、捕捉追尾部によって捕捉追尾された光ビームが波面変調部２１へ入射する。捕捉追尾部は、例えば、ジンバルミラー、ステアリングミラー、エリアセンサ、４分割センサなどからなる。 Further, in the second to fourth embodiments, an acquisition tracking unit may be provided in the preceding stage of the wavefront modulation unit 21. That is, the light beam captured and tracked by the capture and tracking unit is incident on the wavefront modulation unit 21. The capture tracking unit includes, for example, a gimbal mirror, a steering mirror, an area sensor, a quadrant sensor, and the like.
ジンバルミラーは第２の実施形態から第３の実施形態に記載した光制御装置を搭載した光空間通信装置の指向方向を広い領域で粗く制御する。ステアリングミラーは光空間通信装置の指向方向を狭い領域で高精度に制御する。エリアセンサは入射した光ビームから光空間通信装置の指向方向を広い領域で粗く検出する。４分割センサは入射した光ビームから光空間通信装置の指向方向を狭い領域で高精度に検出する。捕捉追尾部を備えると、光空間通信装置の少なくとも一方、あるいは双方が、人工衛星や航空機などの移動体に搭載されている場合、捕捉追尾部の効果はより顕著となる。 The gimbal mirror roughly controls the directivity direction of the space optical communication device equipped with the light control device described in the second to third embodiments in a wide area. The steering mirror controls the pointing direction of the optical space communication device with high accuracy in a narrow area. The area sensor roughly detects the directivity direction of the space optical communication apparatus in a wide area from the incident light beam. The quadrant sensor detects the directivity direction of the optical space communication device from the incident light beam with high accuracy in a narrow area. When the acquisition tracking unit is provided, the effect of the acquisition tracking unit becomes more prominent when at least one or both of the optical space communication devices are mounted on a moving body such as an artificial satellite or an aircraft.
〔第５の実施形態〕続いて、本発明の第５の実施形態について詳細に説明する。図１０は本発明の第５の実施形態である光制御装置５および光空間通信装置の構成を示すブロック図である。第５の実施形態の光制御装置５は、第２の実施形態の光制御装置２と同じ構成であり、第５の実施形態の光空間通信装置は、第２の実施形態の光制御装置２に捕捉追尾部２４が追加された構成である。なお、第５の実施形態の制御部１１、光強度演算部１８は、第２の実施形態の制御部１１、光強度演算部１０とは異なる形態である。それ以外の構成部品は第２の実施形態の光制御装置２と同じであり、それらの説明は省略する。 [Fifth Embodiment] Next, a fifth embodiment of the present invention will be described in detail. FIG. 10 is a block diagram showing the configuration of the light control device 5 and the optical space communication device according to the fifth embodiment of the present invention. The light control device 5 of the fifth embodiment has the same configuration as the light control device 2 of the second embodiment, and the optical space communication device of the fifth embodiment is the light control device 2 of the second embodiment. In this configuration, a capture tracking unit 24 is added. The control unit 11 and the light intensity calculation unit 18 of the fifth embodiment are different from the control unit 11 and the light intensity calculation unit 10 of the second embodiment. Other components are the same as those of the light control device 2 of the second embodiment, and a description thereof will be omitted.
図１０を参照して、捕捉追尾部２４は上述した構成および機能を備えている。さらに、捕捉追尾部２４に入射する光ビームをエリアセンサ、または、４分割センサで検出する。検出した光強度分布の情報を有する電気信号を光強度演算部１８へ出力する。 Referring to FIG. 10, the capture tracking unit 24 has the above-described configuration and function. Further, the light beam incident on the capture tracking unit 24 is detected by an area sensor or a four-divided sensor. An electrical signal having information on the detected light intensity distribution is output to the light intensity calculation unit 18.
光強度演算部１８は、捕捉追尾部２４からの電気信号を入力し、受光強度を演算し、その情報を含んだ受光強度情報信号を制御部１１へ出力する。 The light intensity calculation unit 18 receives an electrical signal from the capture tracking unit 24, calculates the received light intensity, and outputs a received light intensity information signal including the information to the control unit 11.
なお、第５の実施形態の波面センサ２３では、光ビームの進行方向（波面センサ２３へ入射する方向）に交差する２次元面内の複数領域の、位相あるいは位相の傾きの情報が含まれた電気信号を波面演算部１４に出力しているのみである。 Note that the wavefront sensor 23 of the fifth embodiment includes information on the phase or the gradient of the phase of a plurality of regions in a two-dimensional plane that intersects the traveling direction of the light beam (the direction of incidence on the wavefront sensor 23). Only the electrical signal is output to the wavefront computing unit 14.
このように、ＣＣＤ素子やＣＭＯＳ素子を用いる波面センサ２３よりも空間分解能が低い捕捉追尾部の受光センサ（例えば、エリアセンサや４分割センサ）が取得した光強度分布の情報に基づいて受光強度を演算する。したがって、第２の実施形態から第４の実施形態より光強度演算部の演算量を低減することができる。 As described above, the received light intensity is calculated based on the information of the light intensity distribution acquired by the light receiving sensor (for example, the area sensor or the four-divided sensor) of the acquisition and tracking unit having a spatial resolution lower than that of the wavefront sensor 23 using the CCD element or the CMOS element. Calculate. Therefore, the calculation amount of the light intensity calculation unit can be reduced from the second embodiment to the fourth embodiment.
また、第２の実施形態から第５の実施形態のおける光制御方法では、制御部１１が光の増幅を停止あるいは低下させる光増幅制御信号を出力したのち（第１の実施形態のステップＳ３、第２の実施形態から第４の実施形態のステップＳ１３）、制御信号１１が波面収差（もしくは球面収差）を改善する目標収差信号を出力している（第１の実施形態のステップＳ４、第２の実施形態から第４の実施形態のステップＳ１４）。しかし、これに限るものではない。上述したステップの間に、制御部１１が、受光強度情報信号が閾値以下であるかを監視するステップを挿入しても良い。 In the light control method according to the second to fifth embodiments, after the control unit 11 outputs an optical amplification control signal for stopping or reducing the amplification of light (step S3 in the first embodiment, In step S13 of the second to fourth embodiments, the control signal 11 outputs a target aberration signal for improving wavefront aberration (or spherical aberration) (steps S4 and second of the first embodiment). To step S14) of the fourth to fourth embodiments. However, it is not limited to this. Between the above-mentioned steps, the control unit 11 may insert a step of monitoring whether the received light intensity information signal is equal to or less than a threshold value.
なお、本発明は上記実施形態に限定されるものではなく、請求の範囲に記載した発明の範囲内で、種々の変形が可能であり、それらも本発明の範囲内に含まれるものであることはいうまでもない。 The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.
この出願は、２０１３年３月１９日に出願された日本出願特願２０１３－０５６３９４を基礎とする優先権を主張し、その開示の全てをここに取り込む。 This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2013-056394 for which it applied on March 19, 2013, and takes in those the indications of all here.
　１　　光制御装置
　２　　光制御装置
　３　　光制御装置
　４　　光制御装置
　５　　光制御装置
　９　　検出部
　１０　　光強度演算部
　１１　　制御部
　１２　　目標波面演算部
　１３　　波面制御部
　１４　　波面演算部
　１５　　波面補償演算部
　１６　　保護時間タイマ
　１７　　波面記憶部
　２１　　波面変調部
　２２　　光分割部
　２３　　波面センサ
　２４　　捕捉追尾部
　３０　　光増幅部
　３１　　光集光部
　３２　　光ファイバ
　３３　　光ファイバアンプ
　３４　　励起光源
　３５　　受光部 DESCRIPTION OF SYMBOLS 1 Light control apparatus 2 Light control apparatus 3 Light control apparatus 4 Light control apparatus 5 Light control apparatus 9 Detection part 10 Light intensity calculation part 11 Control part 12 Target wavefront calculation part 13 Wavefront control part 14 Wavefront calculation part 15 Wavefront compensation calculation part 16 Protection time timer 17 Wavefront storage unit 21 Wavefront modulation unit 22 Light splitting unit 23 Wavefront sensor 24 Acquisition tracking unit 30 Optical amplification unit 31 Light condensing unit 32 Optical fiber 33 Optical fiber amplifier 34 Excitation light source 35 Light reception unit

Claims (10)

  1. 入射光の波面を制御する波面変調手段と、
    　前記入射光の強度情報を取得する検出手段と、
    　前記強度情報に基づいて目標波面を定める制御手段と、
    　前記入射光の波面が前記目標波面と略等しくなるように、前記波面変調手段を制御する波面制御手段、とを備えた
    光制御装置。     Wavefront modulation means for controlling the wavefront of the incident light;
    Detecting means for acquiring intensity information of the incident light;
    Control means for determining a target wavefront based on the intensity information;
    A light control device comprising: wavefront control means for controlling the wavefront modulation means so that the wavefront of the incident light is substantially equal to the target wavefront.
  2. 前記制御手段は、前記入射光の強度を増幅する光増幅手段の増幅率を制御する請求項１に記載の光制御装置。 The light control apparatus according to claim 1, wherein the control unit controls an amplification factor of an optical amplification unit that amplifies the intensity of the incident light.
  3. 前記制御手段は、前記増幅率を低減させる場合、前記目標波面の収差を増加させたのち、増加した目標波面の収差を段階的に減少させる請求項２に記載の光制御装置。 The light control apparatus according to claim 2, wherein, when the amplification factor is reduced, the control unit increases the aberration of the target wavefront in a stepwise manner after increasing the aberration of the target wavefront.
  4. 前記波面制御手段は、前記目標波面における位相情報を前記波面変調手段へ出力し、前記波面変調手段は前記位相情報に基づき前記入射光の進行方向に対して交差する面内の位相分布を制御する請求項１から３のいずれか１項に記載の光制御装置。 The wavefront control means outputs phase information at the target wavefront to the wavefront modulation means, and the wavefront modulation means controls a phase distribution in a plane intersecting the traveling direction of the incident light based on the phase information. The light control device according to any one of claims 1 to 3.
  5. 前記入射光の強度を制御する光ファイバアンプと、
    　前記光ファイバアンプに励起光を注入する励起光源、とを更に備え、
    　前記制御手段は、前記波面変調手段によって前記入射光へ付与された前記面内位相分布に応じて、光ファイバアンプへの前記光ビームの結合効率を変化させるとともに、
    　前記励起光源の出力を抑制することで光ファイバアンプにおける光ビームの増幅を抑制する請求項１から請求項４のいずれか１項に記載の光制御装置。     An optical fiber amplifier for controlling the intensity of the incident light;
    A pumping light source for injecting pumping light into the optical fiber amplifier, and
    The control means changes the coupling efficiency of the light beam to the optical fiber amplifier according to the in-plane phase distribution imparted to the incident light by the wavefront modulation means,
    5. The light control device according to claim 1, wherein amplification of a light beam in an optical fiber amplifier is suppressed by suppressing an output of the excitation light source.
  6. 保護時間タイマを更に備え、
    　前記制御手段は、前記強度情報が所定値より小さい場合、前記保護時間タイマにより計測された所定時間の間、前記増幅率の抑制、および増加した前記目標波面の収差の段階的な減少を停止する請求項５に記載の光制御装置。     It further includes a protection time timer,
    When the intensity information is smaller than a predetermined value, the control means stops the suppression of the amplification factor and the stepwise decrease of the increased aberration of the target wavefront for a predetermined time measured by the protection time timer. The light control apparatus according to claim 5.
  7. 前記位相情報を記憶する波面記憶手段を更に備え、
    前記波面目標値として前記波面記憶手段に記憶された前記位相情報を用いる請求項１から請求項５のいずれか１項に記載の光制御装置。     Wavefront storage means for storing the phase information;
    The light control device according to claim 1, wherein the phase information stored in the wavefront storage unit is used as the wavefront target value.
  8. 入射光を捕捉追尾し出射光を送出する捕捉追尾手段と、
    　前記出射光の波面を制御する波面変調手段と、
    　前記波面変調手段からの出射光の一部の強度及び波面を検出する波面センサと、
    　前記波面変調手段からの出射光の一部の強度を制御する光ファイバアンプと、
    　前記光ファイバアンプの強度を制御するために励起光を注入する励起光源と、
    　前記光ファイバアンプからの出射光を受光する受光手段と、
    　前記波面センサで検出した強度情報に基づいて、前記入射光の目標波面を定め、前記出射光の増幅を制御する制御手段と、
    　前記目標波面と前記波面センサが検出した波面とに基づき、前記入射光へ付与する位相情報を出力する波面演算手段、とを備えた光空間通信装置。     Capture and tracking means for capturing and tracking incident light and transmitting emitted light;
    Wavefront modulation means for controlling the wavefront of the emitted light;
    A wavefront sensor for detecting the intensity and wavefront of a part of the emitted light from the wavefront modulation means;
    An optical fiber amplifier for controlling the intensity of a part of the light emitted from the wavefront modulation means;
    An excitation light source for injecting excitation light to control the intensity of the optical fiber amplifier;
    A light receiving means for receiving light emitted from the optical fiber amplifier;
    Control means for determining a target wavefront of the incident light based on intensity information detected by the wavefront sensor and controlling amplification of the emitted light;
    An optical space communication device comprising: wavefront calculation means for outputting phase information to be applied to the incident light based on the target wavefront and the wavefront detected by the wavefront sensor.
  9. 入射光の位相情報と強度情報とを取得し、
    　前記強度情報に基づいて前記入射光の目標波面を決定し、
    　前記入射光の波面が前記目標波面と略等しくなるように、前記入射光の波面を制御する光制御方法。     Obtain the phase information and intensity information of the incident light,
    Determining a target wavefront of the incident light based on the intensity information;
    A light control method for controlling the wavefront of the incident light so that the wavefront of the incident light is substantially equal to the target wavefront.
  10. 前記入射光の波面を制御した後、
    　所定の増幅率で前記入射光を増幅し、
    　前記強度情報に基づいて前記増幅率を制御する
    　請求項９に記載の光制御方法。     After controlling the wavefront of the incident light,
    Amplifying the incident light with a predetermined amplification factor;
    The light control method according to claim 9, wherein the amplification factor is controlled based on the intensity information.
PCT/JP2014/001493 2013-03-19 2014-03-17 Light control device, spatial light communication device using same, and light control method WO2014148027A1 (en)

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