38 results about "Polarization mode dispersion" patented technology

The invention provides a fault identification method and system for a buried optical fiber, and relates to the technical field of computers, the polarization mode dispersion change rate and the time-frequency double-domain disturbance coefficient of an optical signal of a to-be-detected buried optical fiber can be obtained, and the time-frequency double-domain disturbance coefficient is determined according to the amplitude fluctuation coefficient and the frequency offset of the optical signal; under the condition that the polarization mode dispersion change rate is greater than a preset first threshold value and the time-frequency double-domain disturbance coefficient is greater than a preset second threshold value, acquiring environment state information and physical excitation parameters of the buried optical fiber; inputting the environment state information, the polarization mode dispersion change rate, the physical excitation parameter and the amplitude fluctuation coefficient into a pre-trained micro-bending strain identification model to obtain a micro-bending strain state index of the buried optical fiber; and inputting the micro-bending strain state index, the environment state information and the time-frequency double-domain disturbance coefficient into a preset optical fiber fault classification model to obtain a fault identification result of the buried optical fiber. And fault identification can be carried out on the buried optical fiber comprehensively and accurately.

The invention discloses a time delay compensation control method and system for two-way communication of a repeater, particularly relates to the technical field of repeaters, and is used for solving the problem of signal time delay distortion caused by polarization mode dispersion in an optical fiber link. By using polynomial fitting and a frequency domain interpolation algorithm and combining a polarization state time delay spectrum chaos degree index and a phase high-order dynamic variable rate index, the complexity of the model is dynamically adjusted, an accurate nonlinear time delay model is generated, and the defect of nonlinear time delay modeling in a traditional method is overcome; the time delay compensation amount is reversely calculated based on the model and mapped into a phase predistortion parameter, a full-band time delay gradient compensation matrix is formed, and the time delay dispersion effect in an optical fiber link is effectively compensated through phase predistortion; therefore, the flattening correction of the broadband signal time delay is realized, the demodulation performance of the receiving end signal is improved, the communication quality of the repeater in a high-frequency and large-bandwidth scene is ensured, and the high-precision service requirement is met.

The invention discloses an optical signal wavelength optimization method and device, a storage medium and a processor. In the scheme, wavelength distortion characteristics in original optical signal data are extracted; performing deep analysis on target distortion distribution data constructed according to the distortion category of the wavelength distortion characteristics to obtain nonlinear crosstalk characteristic parameters and polarization mode dispersion characteristic parameters, and determining mapping relation data according to the parameters and parameters of an optical communication system; generating a wavelength correction coefficient corresponding to the optical signal based on the mapping relation data, and adjusting the initial wavelength parameter according to the wavelength correction coefficient and the dispersion characteristic of the optical fiber material to obtain a target wavelength parameter; simulating a distortion change degree of the optical signal in an optical communication system transmission environment based on the target wavelength parameter; and adjusting the target wavelength parameter according to the distortion change degree. The problem that wavelength distortion cannot be effectively suppressed due to the fact that the prior art is difficult to adapt to a dynamically changing transmission environment is solved, and the signal transmission quality of an optical communication system is guaranteed.

The invention discloses an electric orthogonal polarization synchronous control system of a geological microscope. The electric orthogonal polarization synchronous control system comprises six modules including a stokes parameter dynamic sensing unit based on multi-dimensional space vector transformation and a polarization mode dispersion feature extraction unit fusing adaptive weight distribution. The system captures original signals of polarized light through a high-frequency sampling circuit, generates corresponding compensation parameters according to actual parameters of the geological microscope through feature extraction and parameter calculation, generates driving signals in combination with dynamic threshold adjustment, drives an electric polarization component, and ensures control accuracy through closed-loop feedback adjustment. And each unit is also subdivided into functional subunits, such as mapping model updating, threshold acquisition and the like, so that self-adaptive optimization is realized. The multi-modal data interaction and cooperative control unit guarantees data interaction and overall cooperation of all the modules, the system solves the problems that traditional manual adjustment is low in efficiency and poor in precision, and an existing automatic system is insufficient in polarization mode dispersion processing, and the observation performance of the geological microscope is improved.

The invention discloses a timing error estimation method and device for a Nyquist system. The method comprises the following steps: generating a random modulation signal; inserting zero into even bits of the random modulation signal to obtain an initial training sequence; generating a target communication frame based on the initial training sequence and the communication signal; sending the target communication frame to a receiving end of the Nyquist system; and sending the target communication frame to a receiving end, so that the receiving end extracts an initial training sequence in the target communication frame, performing data processing on the initial training sequence to obtain a target training sequence, and performing timing error estimation on the target communication frame based on the target training sequence and a target timing error detection algorithm to obtain a timing error estimation result. According to the method, the tolerance of a timing error detection algorithm to dispersion, polarization mode dispersion effect and differential group delay damage is enhanced, so that accurate timing error estimation can be provided under a complex channel condition, and the method can be widely applied to the technical field of data communication.

The invention discloses a compensation method and device with robustness under a polarization effect, equipment and a storage medium, belongs to the technical field of communication, and solves the problem that the robustness of a communication system is affected under the existing factors such as rapid polarization state disturbance. A compensation method with robustness under a polarization effect comprises the following steps that S1, a transmitting end processing module generates a polarization multiplexing signal, and a pair of pilot frequencies is inserted in each of two polarization directions of the polarization multiplexing signal to obtain a transmitting end signal; s2, sending the sending end signal to a receiving end digital processing module through a link with a polarization effect, extracting a damage matrix at an insertion position by the receiving end digital processing module according to the pilot frequency, and calculating differential group delay and polarization loss according to a channel matrix, and constructing a damage compensation matrix and completing compensation of the link with the polarization effect. The method provided by the invention has high robustness under the condition that polarization rotation and polarization mode dispersion are damaged in a polarization state.

The invention provides a manufacturing method and a manufacturing device of a low-polarization-mode dispersion hollow-core optical fiber, and the manufacturing method comprises the steps: transmitting a hollow-core optical fiber processed and formed by a fiber drawing furnace to a twisting mechanism, enabling the twisting mechanism to enable the hollow-core optical fiber to rotate along the axis direction of the hollow-core optical fiber when the hollow-core optical fiber moves vertically, and enabling the twisting mechanism to rotate along the axis direction of the hollow-core optical fiber; the low-polarization-mode dispersion hollow-core optical fiber is obtained; wherein the number of turns of rotation of the hollow-core optical fiber in the vertical movement is periodically and asymmetrically changed. The twisting mechanism is applied to manufacturing of the hollow-core optical fiber, and polarization mode dispersion of the hollow-core optical fiber is reduced.

A system and method for implementing a Variable Optical Attenuator (VOA) for high optical power handling. The VOA device may include an optical signal attenuation element with a fixed optical path to dump unwanted optical light to a light absorption material. The light absorption material may be thermally managed for reliability. The VOA device may support input light beams having any polarization state or composites of both P and S light. An embodiment of the present invention is directed to managing P light and S light through the VOA device to travel within a same optical path length to minimize Polarization Mode Dispersion (PMD). In addition, P and S polarization beams may be independently attenuated to minimizes Polarization Dependent Loss (PDL).

This invention provides a low-crosstalk signal demodulation device and method for fiber optic laser communication, belonging to the field of fiber optic communication technology. The device includes a fiber optic signal input port, an optical circulator, a polarization beam splitter / combiner module, a balanced photodetector unit, a low-noise amplification and quadrature demodulation module, an adaptive crosstalk cancellation unit, a MIMO equalization and decision unit, and a digital signal output port, connected in series according to the signal flow direction. It also includes a crosstalk monitoring and feedback unit bidirectionally connected to the low-noise amplification and quadrature demodulation module, the adaptive crosstalk cancellation unit, and the MIMO equalization and decision unit. This invention, employing the aforementioned low-crosstalk signal demodulation device and method for fiber optic laser communication, overcomes the limitations of traditional single-domain crosstalk suppression. Through the synergistic effect of optical path, circuit, and algorithm layers, it effectively suppresses crosstalk caused by multi-channel multiplexing, polarization mode dispersion, and backscattering, significantly improving demodulation accuracy, anti-interference capability, and system stability.

A control device controls operation of a compensation device that compensates for birefringence and / or polarization mode dispersion experienced by signal light propagating in an optical transmission path by digital signal processing using a finite impulse response filter, the control device having: a detection signal receiving section that receives a detection signal that is a signal representing a detection result of a detection device that optically detects a polarization fluctuation in the optical transmission path; and a setting section that decides a setting related to an update frequency or update interval of a tap number of the finite impulse response filter or a setting related to an update frequency or update interval of a tap coefficient of the finite impulse response filter based on the detection result of the detection device.

A method and system of measuring the PMD of an optical fiber under test (FUT). A polarization-sensitive optical time domain reflectometer (POTDR) is used to inject into the FUT and from a proximal end thereof, a test signal comprising a series of repeated light pulses and detecting a corresponding polarization-analyzed return light signal coming back from the optical fiber and representing back-reflected light from a light reflector connected to a distal end of the FUT. The plurality of polarization-sensitive acquisitions defines at least one pair of acquisitions performed with mutually different but closely-spaced wavelengths and substantially the same state of polarization (SOP). The process may be repeated for a plurality of pairs of acquisitions performed with at least one of a plurality of mutually-different center wavelengths and a plurality of mutually-different SOPs, and a value of the PMD for the FUT is calculated therefrom.

A silicon-photonics co-packaged optical connector (CPO) is disclosed. The connector provides combined multiple shell lens facet with total internal multi-light-path tunneling. Total optical reflection at the multiple lenses ensures minimal loss, preserved polarization mode dispersion (PMD) and controlled numerical aperture (NA). The shell lens design is inspired by the chirality of seashell symmetry when placed in reference to a symmetry axis and the ensuing special flexibility. An exemplary manufacturing process of the CPO with shell lens is also disclosed.

A silicon-photonics co-packaged optical connector (CPO) is disclosed. The connector provides combined multiple shell lens facet with total internal multi-light-path tunneling. Total optical reflection at the multiple lenses ensures minimal loss, preserved polarization mode dispersion (PMD) and controlled numerical aperture (NA). The shell lens design is inspired by the chirality of seashell symmetry when placed in reference to a symmetry axis and the ensuing special flexibility. An exemplary manufacturing process of the CPO with shell lens is also disclosed.

A control device which controls an operation of a compensation device which compensates for birefringence and / or polarization mode dispersion, which is received by signal light having propagated through an optical transmission line, by digital signal processing using a finite impulse response filter includes: a detection signal reception unit which receives a detection signal which is a signal indicating a detection result of a detection device which optically detects polarization fluctuation in the optical transmission line; and a setting unit which decides a setting regarding an update frequency or an update interval of the number of taps of the finite impulse response filter or an update frequency or an update interval of a tap coefficient of the finite impulse response filter, based on the detection result of the detection device.

The invention belongs to the technical field of communication, and particularly relates to a polarization mode dispersion compensation method and system with low complexity and rapid convergence, and the method comprises the steps: obtaining the normalized amplitude weight of a signal through normalization processing according to the characteristic of a signal constellation point module value; a signal passes through a butterfly filter, and depolarization division multiplexing and polarization mode dispersion compensation are carried out; calculating a difference value between a symbol after equalization and a signal constant modulus constant so as to determine an equalizer vector updating direction and scale; according to the method, the normalized amplitude weight of the signal constellation point is calculated, the butterfly filter is used for filtering the signal, then the filter tap matrix is guided to be updated and iterated according to the normalized amplitude weight, and finally the polarization mode dispersion compensation and depolarization multiplexing are realized. Therefore, convergence of the tap matrix is accelerated, a reliable and stable communication system can be provided, and the method has great potential and application prospects in the communication field.

The invention provides an optical fiber polarization mode dispersion distributed measurement method and system, and the method comprises the steps: enabling pulse polarized light to enter a to-be-measured optical fiber with unknown parameters for transmission, and enabling the polarization state of the pulse polarized light to randomly change at different positions of the to-be-measured optical fiber when the pulse polarized light is transmitted in the to-be-measured optical fiber due to a birefringence effect; detecting the polarization state of Rayleigh scattering light of the pulse polarized light, and constructing a polarized light time domain reflection curve; effective features of the polarized light time domain reflection curve are extracted and input into a pre-trained machine learning model, a polarization mode dispersion prediction result of the to-be-measured optical fiber is obtained, and distributed polarization mode dispersion measurement is achieved; compared with a traditional distributed polarization mode dispersion measurement scheme, the method only needs to emit the detection pulse light once, is low in cost and high in precision, does not need to change the optical signal polarization state of the receiving end for multiple times, is simple in system and convenient to install, and effectively improves the measurement efficiency of distributed polarization mode dispersion.

The present invention provides a method for monitoring high-order polarization mode dispersion based on fractional Fourier transform: inserting a training sequence into the transmitted signal, encoding the transmitted signal at the transmitting end, and using upsampling and pulse shaping to compress the signal bandwidth; transmitting the transmitted signal through a long-distance polarization multiplexing coherent transmission link, and performing polarization hierarchical coherent sampling on the high-speed coherent optical signal transmitted through the system at the receiving end by a coherent receiver; sampling the coherent received signal and intercepting the training sequence, and performing fractional Fourier transform and inverse Radon transform on it to reconstruct the time-frequency evolution of the optical signal into a two-dimensional time-frequency image in the standard rectangular coordinate system; combining the two-dimensional time-frequency image with machine learning to extract high-order polarization damage features, and calculating the high-order polarization mode dispersion value of the optical fiber communication system. The present invention realizes the accurate estimation of high-order polarization mode dispersion. The present invention also provides a corresponding device for monitoring high-order polarization mode dispersion based on fractional Fourier transform.

The present invention relates to a wavelength selection device and method with low polarization mode dispersion. It includes: a wavelength selection switch for performing wavelength selection on signal light, which includes an optical fiber collimation array, a polarization processing device based on a polarization beam splitter, and a beam deflection device adapted to the polarization processing device; a polarization mode dispersion compensation unit for compensating the optical path of the first polarized light and the second polarized light, wherein the first polarized light and the second polarized light are incident on the beam deflection device through the polarization mode dispersion compensation unit; after the first polarized light is deflected by the beam deflection device, it returns to the polarization processing device along the optical path of the second polarized light; at the same time, after the second polarized light is deflected by the beam deflection device, it returns to the polarization processing device along the optical path of the first polarized light; when the polarization processing device uses a polarization beam splitter to polarize the signal light in the present invention, the polarization-related loss and polarization mode dispersion can be effectively reduced, and the cost and assembly difficulty of wavelength selection can be reduced.

The invention discloses a QKD system polarization modulation method based on a Sagnac ring. The method comprises the following steps: S1, carrying out beam splitting on an input optical pulse to obtain a first optical pulse and a second optical pulse; s2, clockwise transmitting the first optical pulse along a slow axis of a polarization maintaining optical fiber in a Saganc ring; the second optical pulse is transmitted anticlockwise along the slow axis of the polarization maintaining optical fiber in the Saganc ring; s3, enabling the first optical pulse and the second optical pulse to generate a phase difference; s4, adjusting the first optical pulse and the second optical pulse to be equal in power and orthogonal in polarization state; and S5, performing interference on the first optical pulse and the second optical pulse to complete polarization modulation. According to the invention, phase noise introduced by a transmission medium can be offset well through the Saganc ring, and extra phase compensation is not needed; and the clockwise and anticlockwise optical pulses in the Saganc ring are transmitted through the slow axis of the polarization maintaining optical fiber, so that the influence of polarization mode dispersion and the influence of the action difference of the phase modulator on the optical pulses in different polarization states are avoided, and the stability of the QKD system is improved.

Devices to mitigate polarization mode dispersion are provided. An example device comprises: an input coupler configured to receive an optical signal comprising a first portion in a first polarization mode and a second portion in a second polarization mode, the second polarization mode about perpendicular to the first polarization mode; an output and / or an optical detector; and one or more optical components configured to convey the optical signal from the input coupler to the output and / or optical detector, one or more of the input coupler and the optical component(s) introducing a total differential group delay between the first and second portions. The optical component(s) comprising: a rotating component configured to rotate the first polarization mode of the first portion to the second polarization mode and rotate the second polarization mode of the second portion to the first polarization mode, to adjust the total differential group delay.

The present invention discloses an apparatus for use by a coherent receiver, comprising means for: obtaining a first set of coefficients (A+) indicating a first adaptive filter (A) configured to reduce at least part of polarization mode dispersion in an equalizer of the coherent receiver and a second set of coefficients (w+) indicating a second adaptive filter (w) configured to reduce at least part of the inter-symbol interference in the equalizer of the coherent receiver, determining a first updated set of coefficients (A++) and a second updated set of coefficients (w++) based on the first set of coefficients (A+) and the second set of coefficients (w+), wherein the gains of the first updated set of coefficients (A++) have a predetermined level, and wherein, the output of the equalizer based on the first set of coefficients (A+) and the second set of coefficients (w+) is approximately same as the output of the equalizer based on the first updated set of coefficients (A++) and the second updated set of coefficients (w++), providing the first updated set of coefficients (A++) and the second updated set of coefficients (w++) to the first filter and the second filter respectively.

The invention discloses a reusable fiber drawing furnace, and particularly relates to the field of fiber drawing furnaces, the reusable fiber drawing furnace comprises a furnace frame, an optical fiber drawing furnace is placed on the outer surface of the furnace frame, a clamping plate assembly is arranged on the outer surface of the furnace frame, and the optical fiber drawing furnace is fixed on the outer surface of the furnace frame through the clamping plate assembly; a top frame is arranged above the optical fiber drawing furnace, a chuck is fixedly mounted at the bottom end of the top frame, and a plurality of optical fiber prefabricated parts are fixed through the chuck; a furnace lining is fixedly installed in the optical fiber drawing furnace, and a heating assembly is arranged in the furnace lining. According to the invention, a plurality of optical fiber prefabricated members are fixed through the chuck and can be drawn at the same time, so that the production efficiency is improved; stable temperature field distribution can be formed when a plurality of optical fibers are drawn at the same time, so that the temperature field distribution is kept stable when the optical fibers are drawn; the temperature in the furnace is precisely controlled through the combined use of the thermocouple and the temperature controller, so that an ideal wire drawing environment is provided, the out-of-roundness of the optical fiber is reduced to zero as far as possible, and the connection loss of the optical fiber and the dispersion of a polarizing film are reduced.

The invention relates to the technical field of coherent optical communication signal processing, in particular to a CNN-BiLSTM-based low-complexity coherent optical communication system damage compensation method, which comprises the following steps of: processing a to-be-processed dual-polarization coherent optical signal by adopting a pre-trained CNN-BiLSTM neural network model for low-complexity optical fiber transmission damage compensation, a balanced polarization state signal is obtained; according to the method, dispersion compensation and polarization mode dispersion are mutually constrained and cooperatively optimized in a mode of combining one-dimensional convolution and bidirectional LSTM, so that the model can process dispersion compensation and polarization equilibrium compensation at the same time; one-dimensional convolution is adopted to calculate the phase compensation amount, a dispersion compensation filter of a traditional algorithm is replaced to realize dispersion compensation, dependence on data is reduced, and accuracy is improved; a bidirectional LSTM structure is adopted, a polarization sensing time sequence attention mechanism is combined, and collaborative optimization of dynamic damage balance and low-power-consumption real-time processing is achieved.

The invention provides a multi-core optical fiber capable of reducing polarization mode dispersion. A multi-core optical fiber is provided with a plurality of cores along an optical fiber axis, and a cladding covering the plurality of cores. The plurality of cores and the cladding layer contain silica glass as a main component. The refractive index of each of the plurality of cores is higher than the refractive index of the cladding. The linear expansion coefficient of each of the plurality of cores is greater than the linear expansion coefficient of the cladding. The plurality of cores includes a first core having an elliptical shape in a cross section orthogonal to the optical fiber axis, and one or more second cores different from the first core. The out-of-roundness of the elliptical shape is 0.1% or more. In a cross section orthogonal to the optical fiber axis, the angle formed by a straight line connecting the center of gravity of the first core and the center of gravity of a core group composed of the one or more second cores and a straight line along the long axis of the elliptical shape is 30 degrees or less. The polarization mode dispersion is 0.2 ps / rtkm or less.

The present invention belongs to the technical field of coherent optical communication, and specifically relates to a polarization mode dispersion adaptive equalizer based on approximate calculation. The adaptive equalizer of the present invention is a 16-channel parallel equalizer, and each channel adopts a 9-1 equalizer structure; in this parallel equalizer, a parameter sharing scheme is adopted, and all multipliers are implemented using approximate multipliers; the present invention can reduce the parameters of the equalizer by 38.9%, greatly reduce the scale of the parameters, and reduce the computational complexity; this multiplier can reduce the number of full adders by about 44.6% while ensuring that the average absolute error loss is only 0.31; it can greatly reduce the area and power consumption while ensuring a very small loss of calculation accuracy; the comprehensive results show that compared with the fixed-point structure, the area of the approximate base equalizer is increased by 27.86%, and the power efficiency is increased by 37.88%.

The present application relates to a reticle cartridge having a retention through a reticle compartment wall. The reticle cartridge includes an outer portion including a cartridge door and a cartridge dome, and an inner portion including a bottom plate and a cover. One of the base plate or the cover includes a reticle compartment wall extending toward the other of the base plate or the cover. The reticle compartment wall includes one or more retention features. The cartridge door or the cartridge dome includes one or more actuation surfaces configured to contact the retention feature. The retention feature is configured to be moved by contact with the actuation surface. The retaining feature may be in a position, the positions are configured to secure a reticle within the inner portion of the reticle cartridge when the reticle cartridge is assembled by engaging the base plate with the cover, placing the engaged base plate and the engaged cover within the cartridge dome, and securing the cartridge door to the cartridge dome.

The application discloses a polarization mode dispersion-tolerant dispersion monitoring method and system and electronic equipment, and the method comprises the following steps: firstly, calculating the spectrum autocorrelation function of the X polarization of an input optical signal; determining the first time-domain pulse sequence of the spectrum autocorrelation function on the X polarization according to the spectrum autocorrelation function of the X polarization; calculating the spectrum cross-correlation function between the X polarization and the Y polarization of the input optical signal; determining the second time-domain pulse sequence on the spectrum cross-correlation function according to the spectrum cross-correlation function; determining the pulse peak position according to the first time-domain pulse sequence and the second time-domain pulse sequence; and determining the dispersion value of the target optical signal according to the pulse peak position. The application can tolerate polarization mode dispersion and polarization state rotation, and can be widely applied to the technical field of coherent optical communication.

The invention belongs to the technical field of optical communication, and relates to a method for compensating polarization mode dispersion in an optical fiber channel. The compensation method comprises the following steps: setting and initializing a Kalman state vector, and constructing a state vector covariance matrix; the method comprises the following steps of: partitioning an input damaged signal; each blocked damaged signal is converted to a frequency domain and then multiplied by the constructed polarization mode dispersion compensation matrix to obtain a polarization mode dispersion frequency domain compensated damaged signal, and the signal is converted to a time domain to obtain a polarization mode dispersion compensated time domain matrix; constructing a polarization state rotation compensation matrix and multiplying the polarization state rotation compensation matrix with the time domain matrix after polarization mode dispersion compensation to obtain a filter output signal; constructing an error function based on the ideal signal amplitude and the filter output signal, constructing a Kalman observation matrix in a Jacobian matrix form by using the error function, and updating Kalman gain according to the matrix; and updating the Kalman state vector and the state vector covariance matrix. According to the method, the calculation complexity is reduced on the premise of ensuring the polarization damage balance performance.

The present application discloses a timing error estimation method and apparatus for a Nyquist system. The method comprises: generating a randomly modulated signal; inserting zeros into even-numbered bits of the randomly modulated signal to obtain an initial training sequence; generating a target communication frame based on the initial training sequence and a communication signal; and transmitting the target communication frame to a receiving end of the Nyquist system. The receiving end extracts the initial training sequence from the target communication frame, performs data processing on the initial training sequence to obtain a target training sequence, and performs timing error estimation on the target communication frame based on the target training sequence and a target timing error detection algorithm to obtain a timing error estimation result. The present application enhances the tolerance of the timing error detection algorithm to chromatic dispersion, polarization mode dispersion effects, and differential group delay impairments, thereby providing accurate timing error estimation even under complex channel conditions. The present application can be widely applied in the field of data communication technology.