CN100362379C - Self-adaptive dispersion compensation process and device in polarization mode of broadband - Google Patents
Self-adaptive dispersion compensation process and device in polarization mode of broadband Download PDFInfo
- Publication number
- CN100362379C CN100362379C CNB2005101177495A CN200510117749A CN100362379C CN 100362379 C CN100362379 C CN 100362379C CN B2005101177495 A CNB2005101177495 A CN B2005101177495A CN 200510117749 A CN200510117749 A CN 200510117749A CN 100362379 C CN100362379 C CN 100362379C
- Authority
- CN
- China
- Prior art keywords
- polarization
- compensator
- optical
- mach
- optical fiber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Optical Communication System (AREA)
Abstract
The present invention provides a self-adaptive broadband polarization mode dispersion compensation method and a device using a Mach-Zehnder interference annular chamber compensator on the basis of output polarization state detection. The method and the device measure the polarization state parameters within an adopted frequency band range at the output end of a transmission optical fiber, produce delay balance by using an optical waveguide which is connected in series with a Mach-Zehnder interference annular chamber, and realize the compensation of wideband polarization mode dispersion. The parameter regulation of the present invention, which is based on output polarization state detection and uses the Mach-Zehnder interference annular chamber, can compensate the polarization mode dispersion of wideband optical fibers.
Description
Technical Field
The invention relates to a fiber polarization mode dispersion compensation technology, in particular to a self-adaptive broadband polarization mode dispersion compensation method and a device based on output polarization state detection and by using a Mach Zehnder interference ring cavity compensator.
Background
With the widespread use of optical fiber transmission systems and the increase in transmission distances of the systems, polarization mode dispersion is becoming an obstacle to the limitation of long-distance optical fiber communication systems. Especially in high-speed optical fiber communication systems with transmission rates of 10Gb/s and above, polarization Mode Dispersion (PMD) becomes a major technical obstacle. The PMD effect causes the optical pulse to be split into two polarized pulses along the fast and slow axes as it propagates in the fiber, thereby generating signal distortion at the receiving end, the higher the rate, the more significant the influence of PMD. PMD has randomness which dynamically changes with the fiber lay, ambient conditions. When a system design of an optical network is carried out, the maximum optical channel cost generated by PMD is generally defined as 1dB, and when the maximum optical channel cost is greater than a 1dB threshold value, the system failure caused by PMD is defined. To ensure good system operation, the probability of failure is required to be sufficiently small when the cost of the optical channel generated by PMD exceeds a 1dB threshold. The probability of failure is usually specified to be one minute per year, i.e. 10 -6 Or smaller.
In order to reduce the effects of PMD on an optical fiber transmission system, it is generally necessary to employ corresponding PMD compensation measures. Since in actual use, the PMD of each fiber changes randomly over time, rapid and accurate PMD compensation becomes a technical challenge. Therefore, there is a need for an apparatus that can rapidly and accurately detect PMD values in an optical fiber in a short time and compensate in real time based on the detected PMD values.
Disclosure of Invention
The invention aims to provide an adaptive broadband polarization mode dispersion compensator based on output polarization state detection and utilizing a Mach-Zehnder interference ring cavity compensator so as to solve the technical problem.
The fundamental principle of the method is to measure the PMD value in the used frequency band range at the output end of the transmission fiber and to generate delay equalization by utilizing the planar optical waveguide of the serial Mach-Zehnder interference ring cavity, thereby realizing the broadband polarization mode dispersion compensation.
The invention discloses a self-adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and by using a Mach-Zehnder interference annular cavity compensator, which comprises the following steps of:
the optical signal of the output end transmitted by the optical fiber is coupled to a compensation branch of the detection branch;
presetting a plurality of detection frequency points in a transmission bandwidth of an optical fiber needing compensation;
a ferroelectric liquid crystal retarder (FLC) in the detection branch circuit rapidly converts the polarization state of input light under the control of a control unit, and is matched with a polarizer to sequentially filter the left-hand circular polarization, the right-hand circular polarization, the 0-degree linear polarization, the 45-degree linear polarization and the 90-degree linear polarization components of an input light signal, and the passed light beam reaches a diffraction grating;
the diffraction grating in the detection branch diffracts the incident light after polarization filtering and frequency point filtering into each frequency beam near the frequency point and irradiates the detector array arranged in parallel;
the detector arrays arranged in parallel in the detection branch circuit detect the light intensity of each diffraction frequency beam near one frequency point and transmit a light intensity signal to the controller;
the controller firstly collects light intensity signals of diffraction frequency light beams of left-handed circular polarization, right-handed circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization light near one frequency point respectively, calculates polarization state parameters of the frequency point according to the light intensity signals, and then calculates the polarization state parameters of other preset frequency points in turn in the same way, so that the direction of a total polarization state vector of the transmission bandwidth of the detected optical fiber is calculated according to a Poincare sphere measurement method;
the controller decomposes the total polarization state vector of the optical fiber transmission bandwidth in three mutually orthogonal directions, calculates components in the three directions, calculates coupling coefficient parameters of each group of Mach-Zehnder interference annular cavities of the three-section compensator in the compensation branch circuit according to the three components, and controls the temperature of two arms of each group of Mach-Zehnder interference annular cavities in the three-section compensator according to the coupling coefficient parameters, so that the unit amplitude response of the three-section compensator is controlled through the thermo-optical effect to compensate the polarization vectors in the three orthogonal directions respectively.
The self-adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and by using the Mach-Zehnder interference annular cavity compensator is characterized by comprising the following steps of:
the polarization disturbance is carried out on the transmitted optical signal in front of the optical fiber input end, namely the polarization mode of the transmitted optical signal entering the optical fiber is changed, the polarization state vector of the optical fiber transmission bandwidth detected by the detection branch circuit after the polarization disturbance and calculated by the controller is averaged with the polarization state vector which is not detected by the polarization disturbance and calculated, and the more accurate total polarization state vector of the optical fiber transmission bandwidth is obtained.
The invention relates to an adaptive broadband polarization mode dispersion compensation device based on output polarization state detection and utilizing a Mach-Zehnder interference annular cavity compensator, which comprises a coupler, a detection branch, a controller and a compensation branch, wherein the coupler couples an optical signal at the output end of a compensated optical fiber to the detection branch and the compensation branch, the detection branch further comprises a ferroelectric liquid crystal retarder, a polarizer, a diffraction grating and a detector array arranged in parallel, and the compensation branch further comprises a polarization beam splitter, a first optical waveguide, a second optical waveguide, a first 90-degree polarization rotator, a first section of compensator, a first 90-degree polarization rotator, a first 50-to-50 direction coupler, a second section of compensator, a second 50-to-50 direction coupler, a third section of compensator, a second 90-degree polarization rotator and a polarization beam combiner;
characterized in that in the detection branch:
a ferroelectric liquid crystal retarder (FLC) in the detection branch rapidly switches the polarization state of the input light under the control of the control unit,
the polarizer is matched with the ferroelectric liquid crystal delayer to filter the left circular polarization, the right circular polarization, the 0-degree linear polarization, the 45-degree linear polarization and the 90-degree linear polarization components of the input optical signal in sequence, the light beam passing through reaches the diffraction grating,
the diffraction grating diffracts the incident light after polarization filtering and frequency point filtering into various frequency beams near frequency points and irradiates the beams on a detector array arranged in parallel,
the detector arrays arranged in parallel detect the light intensity of each diffraction frequency beam near one frequency point and transmit a light intensity signal to the controller;
in the compensation branch:
each section of the first, second and third compensators comprises two groups of Mach-Zehnder interference annular cavities with a plurality of adjustable coupling coefficients, the two groups of Mach-Zehnder interference annular cavities are respectively connected in series in the first optical waveguide and the second optical waveguide, each Mach-Zehnder interference annular cavity adjusts the coupling coefficient by adjusting the temperature of two arms of the annular cavity, so that the unit amplitude response of the optical waveguide in each section is changed, the polarization beam splitter divides an optical signal to be compensated into two beams to be respectively input into the first optical waveguide and the second optical waveguide,
the first 90-degree polarization rotator in the second optical waveguide rotates the polarized light in the second optical waveguide by 90 degrees so that the polarization directions of the polarized light in the first and second optical waveguides are the same,
the first stage compensator comprises two groups of Mach-Zehnder interference annular cavities, each group is respectively connected in series in the first and second optical waveguides,
the first and second optical waveguides are commonly connected in series with a first 50 to 50 directional coupler after passing through the first section compensator,
the second stage compensator includes two sets of Mach-Zehnder interference ring cavities, each set being connected in series in the first and second optical waveguides,
the first and second optical waveguides are connected in series with a second 50: 50 directional coupler after passing through the second section compensator,
the third stage compensator comprises two groups of Mach-Zehnder interference annular cavities which are respectively connected in series in the first optical waveguide and the second optical waveguide,
a second 90-degree polarization rotator in the second optical waveguide rotates the polarized light in the second optical waveguide by 90 degrees again, so that the polarization directions of the polarized light in the first and second optical waveguides are orthogonal,
the polarization beam combiner mixes the polarized light of the first optical waveguide and the polarized light of the second optical waveguide into an optical signal subjected to polarization compensation;
the controller firstly collects light intensity signals of diffraction frequency light beams of left-handed circular polarization, right-handed circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization light near one frequency point respectively, calculates polarization state parameters of the frequency point according to the light intensity signals, and then calculates the polarization state parameters of other preset frequency points in turn in the same way, so that the direction of a total polarization state vector of the transmission bandwidth of the detected optical fiber is calculated according to a Poincare sphere measurement method;
the controller decomposes the total polarization state vector of the optical fiber transmission bandwidth in three mutually orthogonal directions, calculates components in the three directions, calculates coupling coefficient parameters of each group of Mach-Zehnder interference annular cavities of the three-section compensator in the compensation branch circuit according to the three components, and controls the temperature of two arms of each group of Mach-Zehnder interference annular cavities in the three-section compensator according to the coupling coefficient parameters, so that the unit amplitude response of the three-section compensator is controlled through a thermo-optical effect to compensate the polarization vectors in the three orthogonal directions respectively.
The self-adaptive broadband polarization mode dispersion compensation device based on output polarization state detection and utilizing the Mach-Zehnder interference annular cavity compensator is characterized in that: and a polarization disturbing device is arranged in front of the compensated optical fiber input end, and is used for carrying out polarization disturbance on the transmitted optical signal in front of the optical fiber input end, namely changing the polarization mode of the transmitted optical signal entering the optical fiber, and averaging the polarization state vector of the optical fiber transmission bandwidth, which is detected by the detection branch circuit after the polarization disturbance and calculated by the controller, with the polarization state vector which is not detected and calculated by the polarization disturbance, so as to obtain more accurate total polarization state vector of the optical fiber transmission bandwidth.
The invention can adaptively compensate the polarization mode dispersion of the broadband optical fiber by using the output polarization state detection and utilizing the parameter adjustment of the Mach-Zehnder interference annular cavity, and can realize the rapid and real-time polarization mode dispersion compensation.
Drawings
FIG. 1 is a schematic diagram of a structure of an adaptive broadband polarization mode dispersion compensation device based on output polarization state detection and utilizing a Mach-Zehnder interference ring cavity according to the present invention;
FIG. 2 is a schematic diagram of the internal structure of a Mach-Zehnder interference annular cavity with adjustable parameters used in each section of compensator in the compensation branch of FIG. 1;
fig. 3 is a schematic diagram of the structure of the compensating branch of the apparatus of the present invention shown in fig. 1.
Detailed Description
The method and apparatus of the present invention will be described in detail below with reference to the accompanying drawings.
First, the basic technical principle of the present invention is explained in detail. The detection compensation mode of the invention is to measure the optical fiber at the output end of the transmission optical fiberPolarization principal state vector in the transmitted bandAn all-optical pass filter (APF) composed of Mach-Zehnder interference annular cavities is used as a three-stage compensator, and delay equalization is generated by adjusting the coupling coefficient of the Mach-Zehnder interference annular cavities, so that a characteristic matrix synthesized by the optical fiber and the compensator is independent of frequency, and broadband PMD compensation is realized. The general structure of the device of the present invention is shown in fig. 1.
According to the Ponga sphere measurement method widely used in the measurement of the polarization mode dispersion of an optical fiber, an optical signal in a frequency band range of omega to omega + delta omega is transmitted through the optical fiber, and then the trajectory of the state of polarization (SOP) is output at each frequency measured by a polarimeterCan be approximated as a circular arc on a Poincare sphere, and the axial direction of the circular arc is the polarization Principal State (PSP) vector of the optical fiber
The length of the arc is proportional to the Differential Group Delay (DGD), i.e. the length of the polarization principal state vector
Therefore, the polarization state of the optical signal output in the range of omega to omega + delta omega is measured through the optical fiber transmission band
The principal polarization vector of the fiber can be calculated
In the measuring method adopted by the invention, in order to increase the accuracy of the calculation of the polarization main state of the optical fiber, polarization disturbance is added at the input end of the optical fiber, namely, the polarization mode when the optical signal enters the optical fiber is changed. After the optical signal is subjected to polarization disturbance, the polarization state measured at the output end of the optical fiberThe track is set as
For the same frequency band range, the output optical signal polarization state without disturbanceWith disturbed polarization state of the output optical signal
Different circular arc tracks are generated on the Poincare sphere, but the two circular arcs theoretically should have the same polarization Principal State (PSP) direction due to transmission through the same optical fiber. Thus, the polarization state can be measured by subjecting the optical signal to no polarization perturbation
With the state of polarization measured by the polarization perturbation
Common for calculating principal polarization vector of optical fiber
The accuracy of the calculated polarization dominant state can be further improved. In case multiple polarization perturbations are used, the measurement accuracy of the polarization dominant state is further increased. Since Polarization Mode Dispersion (PMD) has randomness, which dynamically changes with the laying condition of the optical fiber and the surrounding environmental conditions, and the changing interval varies from several milliseconds to several minutes, PMD (PMD) compensation requires the polarization state measurement of the output optical signal within the range of the optical fiber transmission band to be completed within 1 millisecond. In the method of the invention, the frequency and the polarization mode of the light signal transmitted by the ferroelectric liquid crystal retarder are controlled by the controller, only the light signal which is near a certain frequency point in the optical fiber frequency band and has the left-hand circular polarization, the right-hand circular polarization, the 0-degree linear polarization, the 45-degree linear polarization and the 90-degree linear polarization is allowed to transmit through the ferroelectric liquid crystal retarder,after the polarized light signals near the frequency point pass through the polarizer, different frequency component spaces of the light signals near the frequency point are scattered onto the detector array arranged in parallel by the diffraction grating, and the light intensity of each frequency component is measured at the same time, so that the output polarization state is greatly improved
The detection speed of (2). By attaching to a certain frequency pointAnd detecting the intensity of various kinds of polarized light nearby to determine the polarization state parameters of the signal light near the frequency point. The transmission frequency point of the ferroelectric liquid crystal retarder is controlled by the controller, a plurality of frequency points are sequentially selected to traverse the whole optical fiber transmission frequency band range, and then the polarization state vector on the whole frequency band is obtained
The speed of frequency point selection and conversion of the ferroelectric liquid crystal retarder can be adjusted and controlled according to practical application conditions, and the device can simultaneously measure the polarization states of more than 100 frequency points in the 70nm wavelength range on the 1530nm-1600nm transmission wave band in 1 millisecond by matching with the diffraction grating, and the polarization states of the 100 frequency points are combined to form the polarization state vector of the optical fiber on the whole frequency bandThe interval delta f between each measurement frequency point in the transmission band depends on the bandwidth of the polarization main state, and the bandwidth of the PSP is generally taken as 
Is the measured fiber mean Differential Group Delay (DGD) value, which can be determined from the polarization coefficient of the fiber and the length of the fiber. The principal polarization vector of the fiber is considered to remain unchanged over the bandwidth of the principal polarization state. In the measurement of the method of the present invention, take
For one passIf the period of the optical pulse signal transmitted by the optical fiber for transmitting a single optical channel signal is P, the polarization state of the optical signal in the range of 3/P near the center frequency of the optical signal needs to be monitored, and the measurement needs to be selected
And (4) frequency points. If the optical signals are subjected to N polarization disturbances at the input end of the optical fiber when each measurement frequency point is measured, the polarization state parameters of the single optical channel signal frequency range need to be measured for all selected frequency points in total
Next, the process is carried out. For example, the average DGD of the transmission fiber is 50% of the pulse period T of the transmission optical signal, and 192 times of measurement are required to measure the polarization state parameter of the single optical channel signal with the secondary polarization disturbance N = 2. And then calculating the polarization principal state vector of the optical fiber according to the polarization state parameter of the optical signal.
By adopting the method of the invention, the polarization principal state vector is calculated
Then, each set of control signals of the three-stage compensator in the compensation branch in the device of the present invention is further calculated according to the polarization dominant state vector of the optical fiber, and the structure of the compensation branch is shown in fig. 3. The technical specific principle of the compensation branch is as follows:
firstly, the polarization main state vector of the optical fiberDecomposition into three components, equation 1
In the device of the invention, three sections of compensators are arranged in a compensation branch, the first section of compensator is formed by respectively connecting N1 Mach-Zehnder interference annular cavities in series in a first optical waveguide and a second optical waveguide,the second section of compensator is respectively connected with N2 Mach-Zehnder interference annular cavities in series in the first optical waveguide and the second optical waveguide, and the third section of compensator is respectively connected with N3 Mach-Zehnder interference annular cavities in series in the first optical waveguide and the second optical waveguide. The first section of compensator is used for rotating the polarization main state of the optical fiber around {1, 0} in Stokes space by an angle theta 1 (ω), a function of frequency; the second stage compensator is used for rotating the polarization main state of the optical fiber around 0,1 in Stokes space by an angle theta 2 (ω), also a function of frequency. The first stage compensator plus the second stage compensator act as a frequency dependent polarization controller to align the polarization dominant state vectors of various frequencies to the same direction, which is selected as {1, 0} in the method of the present invention. The third stage compensator acts to synthesize a frequency dependent variable dgd delay(DGD) function tau 3 (ω)＝dθ 3 (ω)/d ω), polarization mode dispersion is finally eliminated in the {1, 0} directions. Calculation of principal polarization state vector of optical fiber by measurement
The rotation angle required to be synthesized in the Stokes space in each section of compensator can be calculated. In Stokes space, the rotation matrix of the first stage compensator is represented by equation 2:
the rotation matrix of the second stage compensator is represented by equation 3:
the principal polarization vectors of the first stage compensator and the second stage compensator are represented in equation 4:
thus, after the compensation of the first and second compensators, the polarization principal state vector of the transmission fiber
Represented by equation 5:
after the compensation by the first and second stage compensators, the polarization principal state vectors of all frequencies are arranged in the {1, 0} direction of the Stokes space, and expressed by equation 6:
the angle theta required to rotate in the first and second stage compensators can be calculated by the formula (6) 1 (ω) and θ 2 (ω). The invention adopts a stepwise solving algorithm to determine a certain initial frequency omega first initial Angle of rotation theta 1 (ω initial ) And theta 2 (ω initial ) The rotation angles of the other frequency components can be calculated according to equation 7:
the differential part in equation 7 can be expressed as equation 8:
equation 8 is derived from 6.
Therefore, the angle theta of the main polarization state needing to be rotated in Stokes space in the first and second stage compensators in the whole frequency band range can be obtained 1 (ω) and θ 2 (ω) a numerical value.
After the rotation of the first and second stage compensators, the polarization principal state vectorAs shown in equation 9:
the third stage compensator performs rotation about {1, 0} direction based on the rotation matrix R 3 (omega) pairs
There is no effect. The polarization principal vector of the third stage compensator is expressed as formula 10
The polarization principal state vector after passing through the third stage compensator
Expressed as formula 11
In order that the polarization mode dispersion is zero at all frequencies within the transmission band of the fiber after compensation by the third stage compensator,
it must be zero for all frequencies. Equation 12 can be derived:
and formula 13
The rotation angle theta of the third-stage compensator can be calculated by simultaneous solution 3 (ω)。
At the calculation of the rotation angle theta of each stage 1 (ω)、θ 2 (ω) and θ 3 After the value of (omega), the control parameters of each compensator section can be adjusted to realize the self-adaptive compensation.
Each section of compensator in the compensation branch of the device consists of a plurality of Mach-Zehnder interference annular cavities connected in series on the first optical waveguide and the second optical waveguide, so that each section of compensator has unit amplitude response on all frequencies, and is a universal structural block for optical signal processing. By cascading compensators, the phase response can be adjusted to approximately meet any need, thereby achieving delay equalization. The structure of the Mach-Zehnder ring cavity is shown in figure 2, the coupling coefficient and the coupling frequency of the ring cavity are two main parameters for adjusting the phase response of the compensator, the Mach-Zehnder ring cavities cascaded in series are manufactured on the planar optical waveguide, the temperature of two arms of the ring cavity is controlled, and the parameter adjustment of the ring cavity can be realized through the thermo-optic effect.
In general, N i The phase response of the cascaded Mach-Zehnder compensators is represented by equation 14:
wherein phi is j Determining the resonant frequency, r, of the jth ring cavity j Is its reflection coefficient, and the effective power coupling coefficient k into the cavity j To a
T is the round trip delay of the feedback loop, which is related to the free frequency range (FSR), T = (1/FSR). By varying phi j And r j Any phase response can be obtained. The present invention employs an annular resonator of mach-zehnder interference annular cavity structure as shown in fig. 2. The effective coupling coefficient of the structure is kappa j ＝1-4κ(1-κ)cos 2 (φ κ /2), phi can be varied by thermo-optical effects κ Thereby adjusting k j And r j ，φ j The variation of (c) can also be achieved by thermo-optic effects.
Fig. 3 is a schematic structural diagram of a compensation branch in the device of the present invention. As shown in fig. 3, a three-stage compensator cascade performs the function of polarization mode dispersion compensation on the first and second planar waveguides. Wherein the first and second planar optical waveguides of the first stage compensator are respectively connected in series with N 1 A Mach-Zehnder interference annular cavity, wherein the first and second planar optical waveguides of the second stage of compensator are connected in series with N 2 A Mach-Zehnder interference annular cavity, and a first planar optical waveguide and a second planar optical waveguide of the third stage compensator which are respectively connected in series with N 3 Mach zehnder interferometer ring cavities. The output signal of the transmission fiber is split by a first polarization splitter into a first and a second optical waveguide, i.e. waveguide 1 and waveguide 2 in fig. 3. The optical signal of the waveguide 2 is rotated by 90 ° in the polarization direction by the first 90-degree polarization rotator, so that the polarization directions of the optical signals in the first and second optical waveguides are the same. N of serial waveguides 1 in the first section compensator 1 The cascaded ring cavities will enter the wave1-derived optical signals originally horizontally polarized produce a phase response of 1H (omega), the waveguide 2 is connected in series with N 1 AnThe cascaded ring cavities generate phase response phi on the light which enters the waveguide 2 and is originally vertically polarized 1V (ω). In Stokes space, the transmission through the first stage compensator corresponds to a rotation about the {1, 0} axis by an angle of { φ } 1V (ω)-Ф 1H (ω) }. And then rotated by 90 deg. around 0,1,0 deg. after passing through the first 50 to 50 directional coupler. The second stage compensator is composed of a first optical waveguide and a second optical waveguide which are connected in series with N 2 A cascaded Mach-Zehnder interferometric ring cavity having a rotation angle [ phi 2 ] about a [ 1,0 ] axis V (ω)-Ф 2H (ω) }. After passing through the second 50 to 50 directional coupler, it is rotated 270 around 0,1, 0. Thus, the first and second 50 to 50 directional couplers plus N 2 The combined effect of the cascaded Mach-Zehnder interferometric ring cavities is equivalent to a rotation of φ around 0,1 2V (ω)-Ф 2H (ω) }. N connected in series on first and second optical waveguides in third-stage compensator 3 The effect of the cascaded Mach-Zehnder interferometric ring cavities is equivalent to a rotation of { phi } around {1, 0} 3V (ω)-Ф 3H (ω) }. After passing through the third compensator, the light from the waveguide 2 passes through a second 90 ° polarization rotator. Finally, the light beams of the waveguide 1 and the waveguide 2 are mixed and combined together by a polarization beam combiner.
From the above analysis, the relationship between the phase response required by the waveguide 1 and the waveguide 2 in each section of compensator and the angle of rotation of the optical signal in Stokes space by the respective compensator can be obtained as shown in equation 15:
Ф iV (ω)-Ф iH (ω)＝θ i (ω) (15)
in order to make the homogeneous dispersion generated in the two waveguides only be the group delay, equation 16 needs to be satisfied:
Ф iV (ω)+Ф iH (ω)＝2N i (π-ωT) (16)
thus, we get equation 17:
Ф iV (ω)＝N i (π-ωT)+θ i (ω)/2
(17)
Ф iH (ω)＝N i (π-ωT)-θ i (ω)/2
theta calculated by equation 6 1 (ω)、θ 2 (omega) and number N of Mach-Zehnder interference ring cavities of first and second-stage compensators 1 、N 2 Respectively substituting into equation 17 can calculate a respective set of N on the first and second optical waveguides of the first stage compensator 1 Phase response of individual ring cavities phi 1H (ω)、Ф 1V (omega) and a set of N on the first and second optical waveguides of the second stage compensator respectively 2 Phase response of individual ring cavities phi 2H (ω)、Ф 2V (ω). Further calculates theta from equations 12 and 13 3 (ω) and number of ring cavities N of the third stage compensator 3 Substituting the formula 17 can calculate a group of N on the first and second optical waveguides of the third stage compensator 3 Phase response of individual ring cavities phi 3H (ω)、Ф 3V (ω). Will be phi 1H (ω)、Ф 1V (ω)、Ф 2H (ω)、Ф 2V (ω)、Ф 3H (ω)、 Ф 3V (ω) is substituted into equation 14, and the calculation method of nonlinear fitting is used to determine the φ corresponding to each Mach-Zehnder interferometric ring cavity on the first and second optical waveguides of each compensator κ And gamma κ The parameters are thus dynamically adjusted by thermo-optic effects.
The invention discloses a self-adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and by using a Mach-Zehnder interference annular cavity compensator, which comprises the following steps of: a compensation branch for coupling the output optical signal transmitted through the optical fiber to the detection branch; presetting a plurality of detection frequency points in a transmission bandwidth of an optical fiber needing compensation; a ferroelectric liquid crystal retarder (FLC) in the detection branch circuit rapidly converts the polarization state of input light under the control of a control unit, and is matched with a polarizer to sequentially filter left-hand circular polarization, right-hand circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization components of an input light signal, and the passing light beam reaches a diffraction grating; the diffraction grating in the detection branch diffracts the incident light after polarization filtering and frequency point filtering into each frequency beam near the frequency point and irradiates the detector array arranged in parallel; the detector arrays arranged in parallel in the detection branch circuit detect the light intensity of each diffraction frequency beam near one frequency point and transmit a light intensity signal to the controller; the controller firstly collects light intensity signals of diffraction frequency light beams of left-hand circular polarization, right-hand circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization light near one frequency point respectively, calculates polarization state parameters of the frequency point according to the light intensity signals, then calculates the polarization state parameters of other preset frequency points in sequence in the same way, and calculates the direction of a total polarization state vector of the transmission bandwidth of the detected optical fiber according to a Poincal sphere measurement method; the controller decomposes the total polarization state vector of the optical fiber transmission bandwidth in three mutually orthogonal directions, calculates components in the three directions, calculates coupling coefficient parameters of each group of Mach-Zehnder interference annular cavities of the three-section compensator in the compensation branch circuit according to the three components, controls the temperature of two arms of each group of Mach-Zehnder interference annular cavities in the three-section compensator according to the coupling coefficient parameters, and controls unit amplitude response of the three-section compensator through a thermo-optical effect so as to compensate polarization vectors in the three orthogonal directions respectively. When the adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and utilizing the Mach-Zehnder interference annular cavity compensator is used, in order to increase the polarization state detection precision, polarization disturbance is carried out on a transmitted optical signal in front of the input end of the optical fiber, namely, the polarization mode of the transmitted optical signal entering the optical fiber is changed, the polarization state vector of the optical fiber transmission bandwidth, which is detected through a detection branch path after polarization disturbance and calculated through the controller, and the polarization state vector, which is not detected through polarization disturbance and calculated, are averaged, and the more accurate total polarization state vector of the optical fiber transmission bandwidth is obtained.
FIG. 1 is a schematic structural diagram of an adaptive broadband polarization mode dispersion compensation device based on output polarization state detection and using a Mach-Zehnder interference ring cavity compensator according to the present invention. As shown in fig. 1, the apparatus includes a coupler, a detection branch, a controller, and a compensation branch, where the coupler couples an optical signal at an output end of a compensated optical fiber to the detection branch and the compensation branch, the detection branch further includes a ferroelectric liquid crystal retarder, a polarizer, a diffraction grating, and a detector array arranged in parallel, and the compensation branch further includes a polarization beam splitter, a first optical waveguide, a second optical waveguide, a first 90-degree polarization rotator, a first section compensator, a first 90-degree polarization rotator, a first 50-to-50 directional coupler, a second section compensator, a second 50-to-50 directional coupler, a third section compensator, a second 90-degree polarization rotator, and a polarization beam combiner; characterized in that in the detection branch: a ferroelectric liquid crystal retarder (FLC) in the detection branch circuit rapidly converts the polarization state of input light under the control of a control unit, a polarizer is matched with the ferroelectric liquid crystal retarder to sequentially filter left-hand circular polarization, right-hand circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization components of an input light signal, the passing light beam reaches a diffraction grating, the diffraction grating diffracts the incident light which is subjected to polarization filtering and frequency point filtering into frequency beams near frequency points and irradiates the frequency beams on detector arrays which are arranged in parallel, the detector arrays which are arranged in parallel detect the light intensity of the diffraction frequency beams near one frequency point and transmit light intensity signals to a controller; in the compensation branch: each section of the first, second and third section compensators comprises two groups of Mach-Zehnder interference annular cavities with a plurality of adjustable coupling coefficients, the two groups of Mach-Zehnder interference annular cavities are respectively connected in series in the first optical waveguide and the second optical waveguide, each Mach-Zehnder interference annular cavity adjusts the coupling coefficient by adjusting the temperature of two arms of the annular cavity, so that the unit amplitude response of the optical waveguide in each section is changed, the polarization beam splitter divides an optical signal to be compensated into two beams to be respectively input into the first optical waveguide and the second optical waveguide, the first 90-degree polarization rotator in the second optical waveguide rotates the polarized light in the second optical waveguide by 90 degrees, so that the polarized light in the first optical waveguide and the polarized light in the second optical waveguide have the same direction, the first section compensator comprises two groups of Mach-Zehnder interference annular cavities, and the components are respectively connected in series in the first optical waveguide and the second optical waveguide, the first optical waveguide and the second optical waveguide are connected in series with a first 50-to-50 directional coupler after passing through a first section compensator, the second section compensator comprises two groups of multiple Mach-Zehnder interference annular cavities, each group is connected in series in the first optical waveguide and the second optical waveguide respectively, the first optical waveguide and the second optical waveguide are connected in series with a second 50-to-50 directional coupler after passing through the second section compensator, the third section compensator comprises two groups of multiple Mach-Zehnder interference annular cavities, each group is connected in series in the first optical waveguide and the second optical waveguide respectively, a second 90-degree polarization rotator in the second optical waveguide rotates the polarized light in the second optical waveguide 90 degrees again to enable the polarization directions of the polarized light in the first optical waveguide and the second optical waveguide to be orthogonal, and the polarization beam combiner mixes the polarized light of the first optical waveguide and the polarized light of the second optical waveguide into a light signal after polarization compensation; the controller firstly collects light intensity signals of diffraction frequency light beams of left-handed circular polarization, right-handed circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization light near one frequency point respectively, calculates polarization state parameters of the frequency point according to the light intensity signals, and then calculates the polarization state parameters of other preset frequency points in turn in the same way, thereby calculating the direction of a total polarization state vector of the transmission bandwidth of the detected optical fiber according to a Poincare sphere measurement method; the controller decomposes the total polarization state vector of the optical fiber transmission bandwidth in three mutually orthogonal directions, calculates components in the three directions, calculates coupling coefficient parameters of each group of Mach-Zehnder interference annular cavities of the three-section compensator in the compensation branch circuit according to the three components, and controls the temperature of two arms of each group of Mach-Zehnder interference annular cavities in the three-section compensator according to the coupling coefficient parameters, so that the unit amplitude response of the three-section compensator is controlled through a thermo-optical effect to compensate the polarization vectors in the three orthogonal directions respectively. As shown in fig. 1, the controller in the apparatus of the present invention completes the control of the ferroelectric liquid crystal retarder, completes the data acquisition of the parallel detection array detection signal, and calculates the mach-zehnder interference cavity control parameters in the first stage, the second stage and the third stage compensators by using the all-optical-pass filter synthesis algorithm of the present invention according to the acquired data, thereby realizing the real-time parametric control of the three-stage compensators. The controller is implemented by a Field Programmable Gate Array (FPGA). The structure of the Mach-Zehnder interference annular cavities in the compensators of the first stage, the second stage and the third stage in the device is shown in FIG. 2.
In the self-adaptive broadband polarization mode dispersion compensation device based on the output polarization state detection and utilizing the Mach-Zehnder interference annular cavity compensator, in use, in order to increase the precision of detecting the polarization state, a polarization scrambler is arranged in front of the input end of a compensated optical fiber, the polarization scrambler performs polarization disturbance on a transmitted optical signal in front of the input end of the optical fiber, namely, the polarization mode of the transmitted optical signal entering the optical fiber is changed, and the polarization state vector of the optical fiber transmission bandwidth, which is detected by a detection branch circuit after the polarization disturbance and calculated by a controller, and the polarization state vector which is not detected and calculated by the polarization disturbance are averaged to obtain the total polarization state vector of the more accurate optical fiber transmission bandwidth.
Claims (5)
1. A self-adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and utilizing a Mach-Zehnder interference annular cavity compensator comprises the following steps:
the optical signal of the output end transmitted by the optical fiber is coupled to a compensation branch of the detection branch;
presetting a plurality of detection frequency points in a transmission bandwidth of an optical fiber needing compensation;
the ferroelectric liquid crystal retarder FLC in the detection branch circuit rapidly converts the polarization state of input light under the control of the control unit, and is matched with the polarizer to sequentially filter the left-hand circular polarization, the right-hand circular polarization, the 0-degree linear polarization, the 45-degree linear polarization and the 90-degree linear polarization components of an input light signal, and the passing light beam reaches the diffraction grating;
the diffraction grating in the detection branch diffracts the incident light after polarization filtering and frequency point filtering into each frequency beam near the frequency point and irradiates the detector array arranged in parallel;
the detector arrays arranged in parallel in the detection branch circuit detect the light intensity of each diffraction frequency beam near one frequency point and transmit a light intensity signal to the controller;
the controller firstly collects light intensity signals of diffraction frequency light beams of left-handed circular polarization, right-handed circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization light near one frequency point respectively, calculates polarization state parameters of the frequency point according to the light intensity signals, and then calculates the polarization state parameters of other preset frequency points in turn in the same way, so that the direction of a total polarization state vector of the transmission bandwidth of the detected optical fiber is calculated according to a Poincare sphere measurement method;
the controller decomposes the total polarization state vector of the optical fiber transmission bandwidth in three mutually orthogonal directions, calculates components in the three directions, calculates coupling coefficient parameters of each group of Mach-Zehnder interference annular cavities of the three-section compensator in the compensation branch circuit according to the three components, and controls the temperature of two arms of each group of Mach-Zehnder interference annular cavities in the three-section compensator according to the coupling coefficient parameters, so that the unit amplitude response of the three-section compensator is controlled through the thermo-optical effect to compensate the polarization vectors in the three orthogonal directions respectively.
2. The adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and using a mach-zehnder interferometer ring cavity compensator according to claim 1, characterized by:
the polarization disturbance is carried out on the transmitted optical signal in front of the optical fiber input end, namely, the polarization mode of the transmitted optical signal entering the optical fiber is changed, the polarization state vector of the optical fiber transmission bandwidth detected by the detection branch circuit after the polarization disturbance and calculated by the controller is averaged with the polarization state vector which is not detected by the polarization disturbance and calculated, and the more accurate total polarization state vector of the optical fiber transmission bandwidth is obtained.
3. The adaptive broadband polarization mode dispersion compensation method based on output polarization state detection and using a mach-zehnder interferometer ring cavity compensator according to claim 1, characterized by:
by the formulaCalculating three components of the total polarization state vector in three orthogonal directions according to a formula
And formula
Angle of rotation, by formulaAnd formula
The angle of rotation required by the compensator is calculated by formula
And formulaCalculating control parameters of each group of Mach-Zehnder interference annular cavities on the first optical waveguide and the second optical waveguide in each section of the compensator;
in the above-mentioned formula,
the components of the principal polarization vector in three directions, θ 1 (ω)、θ 2 (ω)、θ 3 (omega) the first, second and third compensators respectively make the polarization principal state of the optical fiber rotate by a certain angle, phi i (ω) is N i Phase response of compensators cascaded with Mach-Zehnder cavities, phi j Is the resonant frequency of the jth ring cavity, r j Is the reflection coefficient of the jth annular cavity.
4. A self-adaptive broadband polarization mode dispersion compensation device based on output polarization state detection and utilizing a Mach-Zehnder interference ring cavity compensator comprises a coupler, a detection branch, a controller and a compensation branch, wherein the coupler couples optical signals at the output end of a compensated optical fiber to the detection branch and the compensation branch, the detection branch further comprises a ferroelectric liquid crystal retarder, a polarizer, a diffraction grating and a detector array arranged in parallel, and the compensation branch further comprises a polarization beam splitter, a first optical waveguide, a second optical waveguide, a first 90-degree polarization rotator, a first section of compensator, a first 90-degree polarization rotator, a first 50-to-50 direction coupler, a second section of compensator, a second 50-to-50 direction coupler, a third section of compensator, a second 90-degree polarization rotator and a polarization beam combiner;
characterized in that in the detection branch:
the ferroelectric liquid crystal retarder FLC in the detection branch circuit rapidly converts the polarization state of input light under the control of the control unit, the polarizer is matched with the ferroelectric liquid crystal retarder to sequentially filter the left-hand circular polarization, the right-hand circular polarization, the 0-degree linear polarization, the 45-degree linear polarization and the 90-degree linear polarization components of the input light signal, the passing light beam reaches the diffraction grating,
the diffraction grating diffracts the incident light after polarization filtering and frequency point filtering into various frequency beams near frequency points and irradiates the beams on a detector array arranged in parallel,
the detector arrays arranged in parallel detect the light intensity of each diffraction frequency beam near one frequency point and transmit a light intensity signal to the controller;
in the compensation branch:
each section of the first, second and third sections of compensators comprises two groups of Mach-Zehnder interference annular cavities with a plurality of adjustable coupling coefficients, the two groups of Mach-Zehnder interference annular cavities are respectively connected in series in the first optical waveguide and the second optical waveguide, each Mach-Zehnder interference annular cavity adjusts the coupling coefficient by adjusting the temperature of two arms of the annular cavity, thereby changing the unit amplitude response of the optical waveguide in each section,
the polarization beam splitter splits the optical signal to be compensated into two beams which are input to the first and second optical waveguides respectively,
the first 90-degree polarization rotator in the second optical waveguide rotates the polarized light in the second optical waveguide by 90 degrees so that the polarization directions of the polarized light in the first and second optical waveguides are the same,
the first stage compensator comprises two groups of Mach-Zehnder interference annular cavities, each group is respectively connected in series in the first and second optical waveguides,
the first and second optical waveguides are commonly connected in series with a first 50 to 50 directional coupler after passing through the first section compensator,
the second stage compensator includes two sets of Mach-Zehnder interference ring cavities, each set connected in series in the first and second optical waveguides,
the first and second optical waveguides are connected in series with a second 50: 50 directional coupler after passing through the second section compensator,
the third stage compensator comprises two groups of Mach-Zehnder interference ring cavities which are respectively connected in series in the first and second optical waveguides,
a second 90-degree polarization rotator in the second optical waveguide rotates the polarized light in the second optical waveguide by 90 degrees again, so that the polarization directions of the polarized light in the first and second optical waveguides are orthogonal,
the polarization beam combiner mixes the polarized light of the first optical waveguide and the polarized light of the second optical waveguide into an optical signal subjected to polarization compensation;
the controller firstly collects light intensity signals of diffraction frequency light beams of left-handed circular polarization, right-handed circular polarization, 0-degree linear polarization, 45-degree linear polarization and 90-degree linear polarization light near one frequency point respectively, calculates polarization state parameters of the frequency point according to the light intensity signals, and then calculates the polarization state parameters of other preset frequency points in turn in the same way, so that the direction of a total polarization state vector of the transmission bandwidth of the detected optical fiber is calculated according to a Poincare sphere measurement method;
the controller decomposes the total polarization state vector of the optical fiber transmission bandwidth in three mutually orthogonal directions, calculates components in the three directions, calculates coupling coefficient parameters of each group of Mach-Zehnder interference annular cavities of the three-section compensator in the compensation branch circuit according to the three components, and controls the temperature of two arms of each group of Mach-Zehnder interference annular cavities in the three-section compensator according to the coupling coefficient parameters, so that the unit amplitude response of the three-section compensator is controlled through a thermo-optical effect to compensate the polarization vectors in the three orthogonal directions respectively.
5. The adaptive broadband polarization mode dispersion compensation apparatus based on output polarization state detection and using a mach-zehnder interferometer ring cavity compensator according to claim 4, characterized by: the polarization disturbing device is arranged in front of the compensated optical fiber input end and is used for carrying out polarization disturbance on the transmitted optical signal in front of the optical fiber input end, namely, the polarization mode of the transmitted optical signal entering the optical fiber is changed, and the polarization state vector of the optical fiber transmission bandwidth, which is detected by the detection branch circuit after the polarization disturbance and calculated by the controller, and the polarization state vector which is not detected by the polarization disturbance and calculated are averaged to obtain more accurate total polarization state vector of the optical fiber transmission bandwidth.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101177495A CN100362379C (en) | 2005-11-10 | 2005-11-10 | Self-adaptive dispersion compensation process and device in polarization mode of broadband |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101177495A CN100362379C (en) | 2005-11-10 | 2005-11-10 | Self-adaptive dispersion compensation process and device in polarization mode of broadband |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1760707A CN1760707A (en) | 2006-04-19 |
| CN100362379C true CN100362379C (en) | 2008-01-16 |
Family
ID=36706845
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005101177495A Expired - Fee Related CN100362379C (en) | 2005-11-10 | 2005-11-10 | Self-adaptive dispersion compensation process and device in polarization mode of broadband |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100362379C (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102096217B (en) * | 2010-12-03 | 2012-11-07 | 武汉光迅科技股份有限公司 | Adjustable dispersion compensation device based on liquid crystal array technology |
| CN103245490B (en) * | 2013-05-10 | 2015-09-16 | 武汉钜风科技有限公司 | The measuring method of polarization modes coupling distribution in polarization maintaining optical fibre |
| CN103475417A (en) * | 2013-09-13 | 2013-12-25 | 武汉邮电科学研究院 | High-speed direct-detection light OFDM system and method based on self-polarization diversity |
| CN103900469B (en) * | 2014-03-20 | 2017-01-11 | 哈尔滨工业大学 | Double-optical-fiber coupling ball microscale sensor based on polarization state detection |
| CN104280364A (en) * | 2014-10-23 | 2015-01-14 | 中国计量学院 | Peanut-shape structure-based refractive index sensor of Mach-Zehnder interferometer |
| CN107870397B (en) * | 2016-09-26 | 2020-02-21 | 华为技术有限公司 | Wavelength selective optical switch |
| CN108873174B (en) | 2017-05-11 | 2019-11-29 | 华为技术有限公司 | It is a kind of to polarize unrelated optical device |
| CN111585645B (en) * | 2019-02-18 | 2023-03-31 | 富士通株式会社 | Polarization state change monitoring device and method caused by optical link and optical receiver |
| CN111835430A (en) * | 2019-04-15 | 2020-10-27 | 无锡雅斯格精密机械有限公司 | Polarization mode dispersion compensation technology in optical transmission system |
| CN111928879B (en) * | 2020-08-26 | 2021-12-07 | 南京英特飞光电技术有限公司 | Polarized Mach-Zehnder interference system with output |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003050984A1 (en) * | 2001-12-13 | 2003-06-19 | Marconi Communications Spa | Polarisation mode dispersion compensator |
| JP2004350285A (en) * | 2003-05-21 | 2004-12-09 | Furukawa Electric North America Inc | Multi-degree pmd compensator for optical fiber transmission system |
| US20050044116A1 (en) * | 2003-08-01 | 2005-02-24 | Poh-Boon Phua | All-frequency PMD compensator and emulator |
| CN1222796C (en) * | 2002-09-13 | 2005-10-12 | 华为技术有限公司 | Polarization mode dispersion compensation process and compensator thereof |
-
2005
- 2005-11-10 CN CNB2005101177495A patent/CN100362379C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003050984A1 (en) * | 2001-12-13 | 2003-06-19 | Marconi Communications Spa | Polarisation mode dispersion compensator |
| CN1222796C (en) * | 2002-09-13 | 2005-10-12 | 华为技术有限公司 | Polarization mode dispersion compensation process and compensator thereof |
| JP2004350285A (en) * | 2003-05-21 | 2004-12-09 | Furukawa Electric North America Inc | Multi-degree pmd compensator for optical fiber transmission system |
| US20050044116A1 (en) * | 2003-08-01 | 2005-02-24 | Poh-Boon Phua | All-frequency PMD compensator and emulator |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1760707A (en) | 2006-04-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100362379C (en) | Self-adaptive dispersion compensation process and device in polarization mode of broadband | |
| US5930414A (en) | Method and apparatus for automatic compensation of first-order polarization mode dispersion (PMD) | |
| US20060098989A1 (en) | System for minimizing or compensating pmd-induced distortion in optical transmission systems and transmission fibres in particular | |
| US20050175339A1 (en) | Dynamic broadband optical equalizer | |
| WO2001091342A2 (en) | Method and system for polarization control and polarization mode dispersion compensation for wideband optical signals | |
| US6765670B2 (en) | Spectrometer module and applications thereof | |
| US8355128B2 (en) | Polarization controller | |
| US6385356B1 (en) | Method and apparatus for compensating for higher order PMD in a fiber transmission system | |
| US20020176645A1 (en) | Polarization mode dispersion compensation in optical transmission media | |
| US6842283B2 (en) | Generation of variable differential group delay | |
| US6380533B1 (en) | Method for measurement of first-and second-order polarization mode dispersion vectors in optical fibers | |
| US6385357B1 (en) | Method and apparatus for compensating for higher order paid PMD in a fiber transmission system at the fiber output | |
| US7043122B2 (en) | PMD compensator based on separation of principal state of polarization control and differential group delay control, and method thereof | |
| US6750956B2 (en) | Method and apparatus for on-line monitoring of polarization mode dispersion in a transmission system | |
| EP1430624B1 (en) | Compensator and method for polarisation-mode dispersion compensation | |
| US7030973B2 (en) | Polarization mode dispersion compensator based on degree of polarization | |
| KR100483023B1 (en) | Polarization mode dispersion compensating device in optical transmission system and method thereof | |
| KR20040045487A (en) | Real-time polarization mode dispersion characterization | |
| Nespola et al. | Real-time demonstration of polarization-multiplexed PAM using a compact silicon photonics device | |
| US20080002972A1 (en) | All Order Polarization Mode Dispersion Compensation with Spectral Interference Based Pulse Shaping | |
| CN115308483A (en) | Microwave frequency measurement system and method based on machine learning | |
| Ke et al. | Beam Polarization Control Technology | |
| Kun et al. | A novel method of automatic polarization measurement and its application to the higher-order PMD measurement | |
| CN117288426A (en) | Polarization dimming-free vector analysis device based on cascade polarization-preserving interferometer | |
| Boehm et al. | Methods for in-service measurement of polarization mode dispersion |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20080116 Termination date: 20091210 |