CN102299477A - Low-coherence semiconductor laser and preparation method thereof - Google Patents
Low-coherence semiconductor laser and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a low-coherence semiconductor laser based on the positive-impedance converter (PIC) technology and a preparation method thereof. A laser module consists of a semiconductor laser, a driving loop, radio frequency (RF) driving current and an automatic power control system. The preparation method of the low-coherence semiconductor laser comprises the following steps that: the alternately changed driving current generated by frequencies in the RF range is input into the semiconductor laser, a part of laser beams is guided into a light detector with the response time exceeding 100ns, the light detector isolates a large amount of stray light and other light feedback noise, the real-time response electronic signals are generated by the laser beams received through the light detector, electronic feedback signals are provided for direct current (DC) and alternating current (AC), and the driving current bias voltage is regulated. The method disclosed by the invention can be used for producing the low-coherence semiconductor laser with good performance.
Description
Technical field
The present invention relates to field of semiconductor lasers, relate in particular to a kind of low semiconductor laser and preparation method thereof that is concerned with radio frequency (RF) modulation drive current.
Background technology
In recent years, low-coherent light has attracted numerous sight, and has become a kind of technology of important absolute remote measurement quasistatic parameter, such as displacement, and temperature, pressure, strain, refractive index etc.Low coherence interference provides a kind of more practical solution for absolute measurement, and the routine of high coherent laser light source interferes irradiation not address these problems.In recent years, make substantial progress in fields such as the development of signal processing, sensor design, transducer, sensor multiplexings.Low coherent laser is applied to as optical coherence tomography (OCT), and it improves spatial resolution and reaches by low temporal coherence.Automated power control (APC) system can adjust laser drive current automatically with the responsive feedback signal.This method comprises the effect of taking precautions against semiconductor laser mode hopping and/or mode assignments.The coherence of semiconductor laser comprises coherence time, coherence length, partial ocoherence, temporal coherence and spatial coherence.The coherence length of desirable semiconductor laser can be calculated according to the Schawlow-Townes formula.In fact, this limit can't reach usually.Mainly be influence, particularly because spontaneous radiation (quantum noise) owing to various noise sources.Secondly, be high power in the chamber, long cavity length and the loss of low resonance will increase coherence length.Therefore, widening of laser line is the effective way that reduces the coherence.As everyone knows, in the prior art, semiconductor laser wavelength has multiple with the reason of drive current variations, comprise the change that changes the laser diode chip refractive index that causes owing to chip temperature, and because the change of the refractive index that the input of free carrier causes.Therefore As time goes on the modulated laser electric current for changing optical maser wavelength, expansion of laser light spectrum and to reduce laser coherence influential effectively, thereby make the power supply reading greater than modulation period reduce the influence of disturbing average time.
Semiconductor laser in reality, the coherence further is subjected to the influence of other factors.As intensity and phase noise coupling influence, temperature drift, and for example environmental factor such as air pressure and humidity etc.The operation of low relevant semiconductor laser depends on the assembly average of the zlasing mode of change at random.By regular change laser drive current, it is below horizontal and between the maximum rated current of a upper frequency to make semiconductor laser be operated in laser threshold.It is so fast that radio frequency (RF) Modulated Semiconductor Laser is thought highly of the speed of multiple opening and closing, to such an extent as to compared with other, do not have longitudinal mode to occupy an leading position all the time.This puts up with and impels the laser multi-mode working.Simultaneously, the laser output spectrum is widened with the form maintenance stable.The typical case who quotes is from United States Patent (USP) 5065401,5175722, and 5197059,5386409,5495464,6049073,6625381 and 6999838.
Summary of the invention
In view of to the low relevant growing demand of semiconductor laser, the objective of the invention is to propose a kind of low semiconductor laser and preparation method thereof that is concerned with based on light feedback and radio frequency (RF) modulation principle.
Purpose of the present invention will be achieved by the following technical programs:
A kind of method of using the preparation of PIC technology to hang down the semiconductor laser that is concerned with, the PIC technology comes from light feedback and rf modulations principle, and time and spectrum stability that described low relevant semiconductor laser improves semiconductor laser reach based on the beam uniformity that hangs down speckle; Described low temporal coherence is based on the vertical pattern that changes with radio frequency modulation, spectrum widen raising with spectrum stability; Described based on low speckle and with the beam uniformity of low spatial coherent correlation transverse mode based on continuous disturbance; May further comprise the steps:
Step 1: the drive current that produces alternate with the frequency of radio-frequency region;
Step 2: the input drive current has the photo-detector of response time above 100 ns to semiconductor laser with a part of laser beam importing, and described photo-detector separates a large amount of stray lights and other light feedback noises;
Step 3: the electrical feedback signal that produces real-time response by the laser beam of photo-detector reception;
Step 4: provide the electrical feedback signal to DC and AC electric current, adjust the drive current bias voltage; Described laser is the continous way operation, thereby produces low coherence, time and spectrum-stable and the uniform outgoing laser beam of space illumination.
Preferably, the method for the low relevant semiconductor laser of above-mentioned preparation, wherein: described semiconductor laser bias voltage can show many longitudinal mode emission near critical value.The modulation of semiconductor laser two-forty is led the system laser spectroscopy owing to transient state spectrum phenomenon is widened.Different modulation indexs produces different modulation depths and widens spectrum.Semiconductor laser has extensive and stable longitudinal mode, but not mode hopping.Thereby semiconductor laser produces low temporal coherence.
Preferably, the method for the low relevant semiconductor laser of above-mentioned preparation, wherein: further comprising the steps of: operate described semiconductor laser with a plurality of transverse modes, described transverse mode is by constantly disturbance of rf modulations (RF).The output facula profile of semiconductor laser is even.This evenly or near evenly being based on the low speckle that the low spatial coherence is correlated with.
A kind of low relevant semiconductor laser according to method for preparing comprises a spectrum, time and spatial stability low-noise semiconductor laser, and described semiconductor laser sends the light from ultraviolet to infrared light wavelength scope.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: described natural oscillation device is a kind of pulse generator that radio frequency repeats burst pulse that produces, and also is included as the polarity transformer of upset burst pulse; Described DC power supply is created in the Dc bias of operating current level, and is modulated by automatic power control system.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: also comprise a shunt, described shunt activates through radiofrequency signal, shunts described laser drive current at any time, thereby closes semiconductor laser at any time; Described Dc bias is arranged on the operating current level by adjustable automatic power control system.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: described natural oscillation device comprises amplifier and/or rectifier.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: described radiofrequency signal is sinusoidal wave, and distortion is sinusoidal wave, rectified sine wave or any non-sinusoidal waveform.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: described automatic power control system also comprises photodiode components and a feedback cycle; Described photodiode components comprises with a light signal that is used for receiving and is converted to the signal of telecommunication, photodiode with response time of at least 100 ns, and one become two parts with semiconductor laser front end face laser beam splitting, and the optical splitter of the laser beam of a part wherein to described photodiode is provided; Described feedback cycle also comprises: the feedback amplifier that amplifies the input photodiode signal of telecommunication, initial value predetermined reference voltage and a comparator according to the semiconductor laser power output, be used for comparing, and adjust the drive current Dc bias according to result relatively with the feedback signal of benchmark.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: described automatic power control system also comprises: the temperature controller that is used to be provided with and keep the semiconductor laser working temperature; A kind of constant-current source that stable drive current is provided; Described constant-current source is by the current feedback stable circulation, and described current feedback circulation comprises: a kind of current sense resistor; Initial value according to the power output of semiconductor laser is formulated reference voltage and a kind of comparator, be used for the feedback signal of benchmark relatively, and adjust the drive current Dc bias according to result relatively.
Preferably, above-mentioned a kind of low relevant semiconductor laser, wherein: also comprise a switch module, regularly the described DC power supply of On/Off is to adjust the pulse direct current bias voltage.
The purpose of this invention is to provide a kind of low relevant semiconductor laser itself and preparation method thereof.This method further comprised in the time, and the operation of stable output laser on spectrum and the space is eliminated or alleviated the noise that mode hopping or mode assignments are induced.The laser operations of low optical noise and spectrum-stable is that the assembly average by instantaneous or unstable state vertical pattern realizes.In order to obtain instantaneous or the unstable state pattern, the amplitude of laser drive current is modulated by radio frequency (RF), in each modulation period vertical pattern is had insufficient time to finish competition or is constantly bothered in operating process.Modulation waveform is that optionally the degree of depth of modulation and frequency can be passed through stochastic model, and various requirements such as power output and laser characteristics are optimized.Because the transient state spectrum phenomenon that rf modulations causes, vertical pattern is changed, and spectrum is widened, and spectrum stability is improved, thereby produces low temporal coherence; Based on the transverse mode of continuous disturbance, the PIC technology also can produce the relevant and relevant therewith low speckle uniform beam of low spatial.
Following constipation closes the embodiment accompanying drawing, the specific embodiment of the present invention is described in further detail, so that technical solution of the present invention is easier to understand, grasp.
Description of drawings
Fig. 1 is the optical arrangement block diagram of the embodiment of the invention 1;
Fig. 2 A is the schematic diagram of the laser diode with automated power control of prior art;
Fig. 2 B is the schematic diagram of the laser diode with automatic power control system of the embodiment of the invention 1;
Fig. 3 A has the sinusoidal waveform of the different modulating degree of depth and the schematic diagram of laser drive current;
Fig. 3 B is the circuit block diagram of drive current of the generation sine wave modulation of the embodiment of the invention 1;
Fig. 4 A is coherence's test result figure of the use PIC technology of the embodiment of the invention 1;
Fig. 4 B is that Fig. 4 A of the embodiment of the invention 1 uses first peak of amplifying in coherence's test result of PIC technology;
Fig. 5 is the use of the embodiment of the invention 1 and does not use the fringe visibility of PIC technology correspondence and the curve chart of O.P.D.;
Fig. 6 A is the coherent fringe photo of the green of not using the PIC technology 520 nanometers of the embodiment of the invention 1;
Fig. 6 B is the coherent fringe photo of green 520 nanometers of the use PIC technology of the embodiment of the invention 1;
Fig. 7 is the live width of the use of the embodiment of the invention 1 and the green 520 Nano semiconductor laser that do not use the PIC technology.
Embodiment
As hereinafter introducing in detail, the present invention has disclosed a kind of low semiconductor laser and preparation method thereof that is concerned with based on the PIC technology.This method has further comprised the laser module of rf modulations drive current, and the front end face photodiode is used in luminous power control, low noise and in the time, the semiconductor laser system of frequency spectrum and spatial stability.
Embodiment 1
A kind of low relevant semiconductor laser of present embodiment, its optical arrangement block diagram as shown in Figure 1, be to comprise a laser diode module 110, described laser diode module 110 comprises a laser diode 150 and collimating lens 120, photodiode components 130 further comprises spectroscope 132, photodiode 135 and beam shaping assembly 140, and beam shaping assembly 140 further comprises telescope 141 and extra camera lens 142.Arrow indication laser optical path.The collimated lens 120 of radiation that send from laser diode 150 collimate.Spectroscope 132 is with the laser output 103b lead-in light electric diode 135 of a part, and light signal wherein converts electric current to.Most laser output 103a enter beam shaping assembly 140.A stable laser beam 101 is to have produced like this.
Shown in Fig. 2 A, be a back side photodiode configuration of prior art, comprise the front 252 and the back side 251.The back side 251 is to comprise the Bragg mirror to the figure layer with high and low refractive index.A photodiode 235 detects the light 204 that extracts from laser diode 150 back sides, and provides feedback signal to the control circuit of adjusting laser output power.Because the thickness and the refractive index of Bragg reflecting layer all depend on temperature, the peak reflectance wavelength of the actual reflectance and the face of returning is responsive to ambient temperature and laser surgey electric current.A little variation of direct reflection may cause that the showing of luminous flux of photodiode changes.Therefore, be converted into the electric current of photodiode, cause optical noise in the fluctuation of temperature and/or drive current.Another shortcoming of prior art is, photodiode is exposed on the laser assembly environment, and may obtain stray light 205 in observation process and introduced extra noise.In mathematic(al) representation, photodiode current
, wherein
Be the photoelectric conversion efficiency electronics, t
bBe the propagation of aspect, back,
Be to propagate according to temperature/current fluctuation to change,
Be laser flux and
Be to enter photodiode the stray light flux is provided.Optical noise is to result from second and the 3rd aspect, and it provides wrong signal for feedback cycle.Because the propagation of aspect, back is one to low,
Minor variations just may cause serious noise.
The contrast prior art can be seen from Fig. 2 B, and the present invention uses photodiode 135 to detect the light that sends from front end face 252, and photodiode 135 is installed in the end face of box body 236 by the internal communication of hole 238 with described box body 236.Also have other holes of two on the box body 236: one is input unthreaded hole 237 and output light hole 239.Be included in the box body 236 is spectroscope 132.Photodiode components 130 is that a dashed rectangle is represented.In this configuration, photodiode sensor is in the outside of laser diode module 110.In operation, the light 203 that sends from front end face 252 enters box body 236 by input unthreaded hole 237.The sub-fraction of spectroscope 132 collimated lights is denoted as 203b, with monitor photodiode 135; Another part cursor is shown 203a, from output light hole 239 outputs.On the mathematics, photodiode current can be expressed as
, t wherein
fBe the propagated of front end face and
Representing the light 203b that branches away to account for the ratio of total laser 203.With respect to the configuration of prior art, the influence of the less relatively temperature fluctuation that is subjected to of signal front end face of being received by photodiode is because t
fCompare t
bMuch higher.The optical noise that this variation that has reduced reflectivity and transmitance is associated.In addition, according to present embodiment, photodiode only accepts to represent the light of actual light power, and isolates with stray light.This has just eliminated possible bulk of optical feedback, has further improved noiseproof feature.The operation of the laser of present embodiment optics low noise and spectrum-stable is that the assembly average by transient state or unstable state longitudinal mode realizes.For the extensive fields laser, spatially uniform and stability that the vertical and horizontal pattern of the transient state of assembly average or labile state is required.In order to obtain transient state or unstable state pattern, RF modulated laser drive current, the competition of the transverse mode of vertical pattern and foundation is incomplete in each modulation period or pattern is continuous disturbance in operating process.Along with waveform, the degree of depth and frequency modulation(FM), more than low noise reached, the optimized choice of the various type of laser of the Wavelength stabilized laser surgey of broad covered area can realize.For example, the drive current that gain guided laser and GaN based laser diode may need reaches regularly that enough to be lower than laser threshold below horizontal, so that suppresses amplified spontaneous emission (ASE) fully and eliminate the memory of the former cycle of operation.Go up the laser beam bundle shape of stable wide spectrum in order to obtain on the space unified and time, need constantly the speed of variation laser drive current enough high, reach stable state to avoid the low order transverse mode.
Now draw the drive current waveform that some have the demonstration meaning.Fig. 3 A shown two in various degree modulation and the sine wave of corresponding light output waveform.Swash figure shown in Fig. 3 A left side has represented dark modulation, and laser is at the ON/OFF mode operating, and the swash figure shown in Fig. 3 A right side has represented shallow modulation, and the laser running is in that ON/OFF continues to interrupt.In the ordinary course of things, the laser spectroscopy of dark modulation result is more extensive than shallow modulation spectrum.
Shown in Fig. 3 B, drive circuit of the present invention is to show with the flow chart form.The sinusoidal wave-wave of amplitude variable is produced by RF oscillator 311, and combines with the constant current that produces from direct current biasing generator 312 in summing junction 313.The sine that radio-frequency oscillator 311 produces becomes amplitude wave and combines in summary 313 constant currents from direct current biasing generator 312.Consequent drive current is with RF waveform input laser diode 150.By beam splitter 132, wherein a part of Laser emission receives and is converted to the signal of telecommunication by photodiode 135.This signal amplifies improving detection sensitivity at feedback amplifier 316 subsequently, and with the predetermined initial value of the power supply selector 314 in the comparator 315 relatively, realize adjusting automatically.Power-supply controller of electric 317 provides the logic control of an ON/OFF direct current and radio circuit: have only as the DC that produced from direct current biasing generator 312 and use radio-frequency oscillator 311 during at predetermined value range, and before DC generator 312 is closed forbidding radio-frequency oscillator 311.This has been avoided laser diode 150 because the infringement that the biasing of intolerable feedback causes.It is reported variously to substitute and change that explanation and operation thereof in the form of system and details can be finished by those skilled prior aries of not running counter to spirit of the present invention.Waveform as shown in Figure 3A is not limited only to sine wave.Other waveforms comprise to be distorted sinusoidal wave and non-sinusoidal waveform and can be used for rf modulations.Non-sinusoidal waveform as square wave and sawtooth waveforms can be by a switch module, a feedback cycle, and delay circuit produces.By regulating direct current biasing and radio frequency amplitude, these waveforms can produce asymmetric biasing to obtain modulation and duty ratio in various degree, and it is required to satisfy practical application.The vertical frequency spectrum of laser may and hang down the concern temporal coherence owing to transient state spectrum phenomenon and broaden, and laser diode is modulated at high data rate.Laser module is realized this method by semiconductor laser, drive circuit, and the rf modulations drive current, automatic power control system is formed.This method has obtained low coherent laser.
That Fig. 4 shows is the result of green 520 Nano semiconductor laser coherence length.Coherence length Michelson interferometer measurement.It is the optical path difference (O.P.D) that is equivalent to 1/e=37% fringe visibility of self-interference laser beam.Fringe visibility V=(Imax-Imin)/(Imax+Imin), wherein Imax and Imin are respectively the maximum and the minimum value of interference strength.Jamming pattern is from the digitlization of CCD camera image, and the analysis of use image analysis packages.Fig. 4 A is to use the coherent fringe figure of the green 520 Nano semiconductor lasers of PIC technology.Ordinate is the fringe visibility that the coherence tests, and abscissa is the distance between two mirrors of Michelson interferometer, is half of optical path difference (O.P.D).The result shows three peaks in seven periodic peaks using the PIC technology; The striped peak period is 1.7 millimeters.Fig. 4 B is the amplification of using first peak in coherence's test result of PIC technology among Fig. 4 A.The optical path difference that is equivalent to 1/e=37% fringe visibility of self-interference laser beam shows 520 nm semiconductor green lasers, and using the coherence length of PIC technology is 280 microns.
Fig. 5 is to use and does not use the fringe visibility of PIC technology correspondence and the curve of O.P.D..Ordinate is the fringe visibility that the coherence tests, and has the fall of a series of crest to surpass coherence length Lc.The crest of these fringe visibilities surpasses coherence length in the OPD value, though amplitude is less relatively, the radiation that expands to bigger OPD value and laser diode may cause measurable mistake when being used for optical detection composition and material.The present invention improves on the basis of existing technology, by the modulating function of an optimization is provided, to reduce the interference effect that the OPD value surpasses coherence length.This method has obtained low coherent laser.For 520 nm semiconductor green lasers, using the coherence length of PIC technology is 280 microns, and the result shows seven periodic peaks using the PIC technology; The striped peak period is 1.7 millimeters.The maximum optical path difference of observing the partially coherent striped is 11 millimeters, and not using PIC technology coherence length is 1.62 centimetres (16.20 millimeters).The maximum optical path difference of observing the each several part coherent fringe is 137 millimeters.
Fig. 6 A and Fig. 6 B are the coherent fringe photos, and photo has disclosed the bright existing difference of degree of coherence when using and not using the PIC technology of green 520 nanometer lasers.Correlation function between two ripples that degree of coherence and relative time postpone to combine fluctuates relevant mutually.The actual measurement of degree of coherence is equivalent to itself utilize the Michelson interferometer to create the wave interference pattern, and measures the visibility that surpasses the phase difference between two ripples of a wavelength change.Fig. 6 A is the coherent fringe photo that does not use green 520 nanometers of PIC technology; Photo has disclosed when optical path difference (O.P.D) is 5.78 millimeters, and the degree of coherence of green 520 nanometer lasers is 0.55.Shown apparent striped.Fig. 6 B is to use the coherent fringe photo of green 520 nanometers of PIC technology; Photo has disclosed photo and has disclosed when optical path difference (O.P.D) is 5.78 millimeters, and the degree of coherence of green 520 nanometer lasers is 0.05.The observability of candy strip is very poor.
Fig. 7 is to use and does not use the live width of the green 520 Nano semiconductor laser of PIC technology.Coherence length
LWith the relation of spectral width be:
Wherein
Be the centre wavelength in source,
Be the refractive index of medium,
It is spectral width.Spectral width
With
Be defined as the complete width of corresponding Gauss's line contour in l/e 0.37 level.Note the gaussian shape of wavelength.Since use the PIC technology, the transient state spectrum phenomenon that rf modulations causes, vertical pattern is changed, and spectrum is widened, and spectrum stability is improved, thereby produces low temporal coherence; Thereby expansion of laser light spectrum also reduces laser coherence effectively.
Present embodiment provides a kind of method of drive current of modulated laser diode, at first determines the modulating function of drive current, comprises the shape of determining modulating function.In preferred embodiments, according to the needs that best laser coherence reduces, spectral waveform is Gauss significantly; Another embodiment is utilized spectral waveform, progressively spreads out the edge to spectrum, not a large amount of discontinuity of the bell waveform of other similar Gausses of picture or the spectrum change of burst.
The present invention still has numerous embodiments, and all employing equivalents or equivalent transformation and all technical schemes of forming all drop within protection scope of the present invention.
Claims (11)
1. one kind is used the relevant semiconductor laser preparation method of hanging down of PIC technology, the PIC technology comes from light feedback and rf modulations principle, and time and spectrum stability that described low relevant semiconductor laser improves semiconductor laser reach based on the beam uniformity that hangs down speckle; Described low temporal coherence is based on the vertical pattern that changes with radio frequency modulation, spectrum widen raising with spectrum stability; Described based on low speckle and with the beam uniformity of low spatial coherent correlation transverse mode based on continuous disturbance; It is characterized in that may further comprise the steps:
Step 1: the drive current that produces alternate with the frequency of radio-frequency region;
Step 2: the input drive current has the photo-detector of response time above 100 ns to semiconductor laser with a part of laser beam importing, and described photo-detector separates a large amount of stray lights and other light feedback noises;
Step 3: the electrical feedback signal that produces real-time response by the laser beam of photo-detector reception;
Step 4: provide the electrical feedback signal to DC and AC electric current, adjust the drive current bias voltage; Described laser is the continous way operation, thereby produces low coherence, time and spectrum-stable and the uniform outgoing laser beam of space illumination.
2. the method for the low relevant semiconductor laser of preparation according to claim 1, it is characterized in that: described semiconductor laser bias voltage can show many longitudinal mode emission near critical value.
3. the method for the low relevant semiconductor laser of preparation according to claim 1, it is characterized in that: further comprising the steps of: operate described semiconductor laser with a plurality of transverse modes, described transverse mode is by the continuous disturbance of rf modulations.
4. low relevant semiconductor laser according to the preparation of the described method of claim 1, it is characterized in that: comprise a spectrum, time and spatial stability low-noise semiconductor laser, described semiconductor laser sends the light from ultraviolet to infrared light wavelength scope.
5. low relevant semiconductor laser according to claim 4 is characterized in that: described natural oscillation device is a kind of pulse generator that radio frequency repeats burst pulse that produces, and also is included as the polarity transformer of upset burst pulse; Described DC power supply is created in the Dc bias of operating current level, and is modulated by automatic power control system.
6. low relevant semiconductor laser according to claim 4, it is characterized in that: also comprise a shunt, described shunt activates through radiofrequency signal, shunts described laser drive current at any time, thereby closes semiconductor laser at any time; Described Dc bias is arranged on the operating current level by adjustable automatic power control system.
7. low relevant semiconductor laser according to claim 4, it is characterized in that: described natural oscillation device comprises amplifier and/or rectifier.
8. low relevant semiconductor laser according to claim 4, it is characterized in that: described radiofrequency signal is for sinusoidal wave, and distortion is sinusoidal wave, rectified sine wave or any non-sinusoidal waveform.
9. low relevant semiconductor laser according to claim 4, it is characterized in that: described automatic power control system also comprises photodiode components and a feedback cycle; Described photodiode components comprises with a light signal that is used for receiving and is converted to the signal of telecommunication, photodiode with response time of at least 100 ns, and one become two parts with semiconductor laser front end face laser beam splitting, and the optical splitter of the laser beam of a part wherein to described photodiode is provided; Described feedback cycle also comprises: the feedback amplifier that amplifies the input photodiode signal of telecommunication, initial value predetermined reference voltage and a comparator according to the semiconductor laser power output, be used for comparing, and adjust the drive current Dc bias according to result relatively with the feedback signal of benchmark.
10. low relevant semiconductor laser according to claim 4, it is characterized in that: described automatic power control system also comprises: the temperature controller that is used to be provided with and keep the semiconductor laser working temperature; A kind of constant-current source that stable drive current is provided; Described constant-current source is by the current feedback stable circulation, and described current feedback circulation comprises: a kind of current sense resistor; Initial value according to the power output of semiconductor laser is formulated reference voltage and a kind of comparator, be used for the feedback signal of benchmark relatively, and adjust the drive current Dc bias according to result relatively.
11. low relevant semiconductor laser according to claim 4 is characterized in that: also comprise a switch module, regularly the described DC power supply of On/Off is to adjust the pulse direct current bias voltage.
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| WO2017177937A1 (en) * | 2016-04-14 | 2017-10-19 | 维林光电(苏州)有限公司 | Speckle laser device based on low time coherence and low spatial coherence, and preparation method therefor |
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