Low-insertion-loss wavelength division multiplexer and control method thereof

Abstract

The invention discloses a low-insertion-loss wavelength division multiplexer and a control method thereof, and relates to the related technical field of wavelength division multiplexers, and the low-insertion-loss wavelength division multiplexer comprises an input port which comprises a plurality of input channels which are used for receiving multi-wavelength multiplexing optical signals; the at least two stages of filtering units are connected stage by stage and are used for carrying out stage-by-stage filtering on the multi-wavelength multiplexing optical signals input by the plurality of input channels and outputting multi-wavelength stage-by-stage filtering signals; and the output port is used for fitting the multi-wavelength step-by-step filtering signal to obtain a beam combination multiplexing optical signal. The technical problems that in the prior art, a wavelength division multiplexer is high in insertion loss, optical signal filtering processing is not accurate, complex and changeable optical signal transmission requirements are difficult to meet, and beam combining and multiplexing efficiency is low are solved. The technical effects of reducing the optical signal transmission insertion loss, improving the optical signal filtering processing precision and flexibility and improving the reliability of an optical communication system are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wavelength division multiplexer and related technologies, in particular to a low insertion loss wavelength division multiplexer and a control method thereof. BACKGROUND

[0002] Wavelength division multiplexing (WDM) is widely used in backbone network, metropolitan area network and many other fields due to its ability to transmit multiple different wavelength optical signals in one optical fiber. However, one of the most prominent problems of traditional wavelength division multiplexer is high insertion loss when processing multi-wavelength multiplexed optical signals. High insertion loss leads to a large amount of energy loss of optical signals during transmission, which not only limits the transmission distance of signals, but also reduces the overall performance and reliability of optical communication systems. In addition, the traditional filtering method cannot accurately classify and process multi-wavelength optical signals, which cannot meet the diversified needs of different services for optical signal quality and transmission characteristics. In a complex optical communication network environment, the composition and characteristics of multi-wavelength optical signals are complex and changeable, and the traditional wavelength division multiplexer is difficult to adapt flexibly, resulting in low signal processing efficiency and affecting the transmission quality of optical signals.

[0003] Therefore, in the related art, there are technical problems of high insertion loss of wavelength division multiplexer, inaccurate filtering and processing of optical signals, difficulty in adapting to complex and changeable optical signal transmission requirements, and low efficiency of beam combining and multiplexing. SUMMARY

[0004] The present application provides a low insertion loss wavelength division multiplexer and a control method thereof, which solves the technical problems of high insertion loss of wavelength division multiplexer, inaccurate filtering and processing of optical signals, difficulty in adapting to complex and changeable optical signal transmission requirements, and low efficiency of beam combining and multiplexing in the prior art, and achieves the technical effects of reducing optical signal transmission insertion loss, improving optical signal filtering and processing accuracy and flexibility, and improving the reliability of optical communication systems.

[0005] The present application provides a low insertion loss wavelength division multiplexer, which comprises: an input port comprising a plurality of input channels for receiving a multi-wavelength multiplexed optical signal; at least two stages of filter units connected in stages for performing stage-by-stage filtering on the multi-wavelength multiplexed optical signal input by the plurality of input channels and outputting a multi-wavelength stage-by-stage filtered signal; and an output port for fitting the multi-wavelength stage-by-stage filtered signal to obtain a beam combined and multiplexed optical signal.

[0006] In a possible implementation, the low insertion loss wavelength division multiplexer further comprises: each stage of filter units comprises a plurality of narrowband filters, wherein the plurality of narrowband filters correspond to the plurality of input channels and respectively receive multiplexed optical signals of corresponding channels.

[0007] In a possible implementation, the low-insertion-loss wavelength division multiplexer further includes: if the at least two filter units include a first filter unit and a second filter unit; filtering, by the first filter unit, the multiple-wavelength multiplexed optical signals input by the multiple input channels to obtain multiple-wavelength first filter signals; inputting the multiple-wavelength first filter signals into the second filter unit to filter to obtain multiple-wavelength second filter signals; and outputting the multiple-wavelength second filter signals as multiple-wavelength step-by-step filter signals.

[0008] In a possible implementation, the low-insertion-loss wavelength division multiplexer further includes: the low-insertion-loss wavelength division multiplexer includes a filter granularity control unit, the filter granularity control unit is connected with the at least two filter units; the filter granularity control unit is configured to set at least two filter granularities according to filter levels of the at least two filter units, and configure filter parameters of the at least two filter units according to the at least two filter granularities; each filter granularity includes corresponding filter parameters, and the filter parameters include a bandwidth, a passband center wavelength, a sideband suppression ratio, and an insertion loss threshold.

[0009] In a possible implementation, the low-insertion-loss wavelength division multiplexer further includes: an insertion loss equalization unit is arranged between the at least two filter units, the insertion loss equalization unit is configured to detect an insertion loss index corresponding to a previous filter unit, the insertion loss index includes an insertion loss value, a bandwidth offset, and a center wavelength drift; and perform insertion loss equalization compensation on filter parameters of a next filter unit according to the insertion loss index.

[0010] In a possible implementation, the low-insertion-loss wavelength division multiplexer further includes: an input end of the output port includes a fitting module; the fitting module is configured to fit the multiple-wavelength step-by-step filter signals to obtain a beam-combined multiplexed optical signal, and the beam-combined multiplexed optical signal is output through the output port.

[0011] In a possible implementation, the low-insertion-loss wavelength division multiplexer further includes: the multiple input channels of the input port are arranged according to a preset wavelength interval, and the preset wavelength interval is 100 GHz or 50 GHz.

[0012] The application further provides a control method of a low-insertion-loss wavelength division multiplexer, including: acquiring multiple-wavelength multiplexed signals received by multiple input channels according to an input port of the low-insertion-loss wavelength division multiplexer; presetting multiple filter granularities for multiple filter units of the low-insertion-loss wavelength division multiplexer, performing multiple-stage filtering on the multiple-wavelength multiplexed signals according to the multiple filter granularities, and outputting multiple-wavelength step-by-step filter signals; and fitting the multiple-wavelength step-by-step filter signals according to an output port of the low-insertion-loss wavelength division multiplexer to obtain a beam-combined multiplexed optical signal.

[0013] In a possible implementation, the control method of the low-insertion-loss wavelength division multiplexer further includes: collecting an insertion loss index of each filter unit in the multi-stage filter unit in real time, the insertion loss index being obtained by weight calculation on an insertion loss value, a bandwidth offset, and a center wavelength drift; and starting an insertion loss equalization unit of the low-insertion-loss wavelength division multiplexer, the insertion loss equalization unit performing insertion loss compensation on a filter parameter of a next-stage filter unit according to the insertion loss index.

[0014] In a possible implementation, the control method of the low-insertion-loss wavelength division multiplexer further includes: obtaining a channel interval of the low-insertion-loss wavelength division multiplexer; determining a range of each filter parameter according to the channel interval of the low-insertion-loss wavelength division multiplexer, where the filter parameter includes a bandwidth, a passband center wavelength, a sideband suppression ratio, and an insertion loss threshold; and dividing the range of each filter parameter by the number of the multi-stage filter unit to obtain a plurality of filter granularities.

[0015] A low-insertion-loss wavelength division multiplexer and a control method thereof are provided in the present application. An input port includes a plurality of input channels, and the plurality of input channels are configured to receive a multi-wavelength multiplexed optical signal. At least two filter units are connected in stages, and are configured to perform stage-by-stage filtering on the multi-wavelength multiplexed optical signal input by the plurality of input channels, and output a multi-wavelength stage-by-stage filtered signal. An output port is configured to fit the multi-wavelength stage-by-stage filtered signal to obtain a beam-combined multiplexed optical signal. The technical problems of high insertion loss of a wavelength division multiplexer, inaccurate optical signal filtering processing, difficulty in adapting to complex and changeable optical signal transmission requirements, and low beam-combining efficiency are solved, and the technical effects of reducing optical signal transmission insertion loss, improving optical signal filtering processing accuracy and flexibility, and improving optical communication system reliability are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments of the present disclosure will be briefly introduced below. In the present application, a flowchart is used to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in sequence. On the contrary, various steps can be processed in reverse order or simultaneously as needed. Meanwhile, other operations can be added to these processes, or a step or several steps can be removed from these processes.

[0017] Figure 1 A control method of a low-insertion-loss wavelength division multiplexer provided by the embodiments of the present application is shown in the flowchart. DETAILED DESCRIPTION

[0018] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below.

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description of this application will be provided in conjunction with the accompanying drawings. The described embodiments should not be considered as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the following description, references to "some embodiments" describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same or different subsets of all possible embodiments and can be combined with each other without conflict. The terms "first" and "second" are used merely to distinguish similar objects and do not represent a specific ordering of objects. The terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, product, or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, products, or devices. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing embodiments of this application only.

[0021] This application provides a low insertion loss wavelength division multiplexer, which includes: The input port includes multiple input channels for receiving multi-wavelength multiplexed optical signals.

[0022] Preferably, the input port is the signal inlet of the entire low insertion loss wavelength division multiplexer, used to access the multi-wavelength multiplexed optical signals in the external optical communication network, and transmit these signals to the subsequent filtering unit for processing, wherein the multi-wavelength multiplexed optical signal refers to a signal transmitted by multiplexing multiple optical signals of different wavelengths in one optical fiber through wavelength division multiplexing technology; the input port includes multiple input channels, and the multiple input channels correspond to multiple independent optical fiber interfaces (such as LC, SC, etc. Standard optical fiber connectors), each channel can individually access one or more multi-wavelength multiplexed optical signals, for example, if the input port contains 4 input channels, it can simultaneously receive optical signals transmitted by 4 optical fibers, and each optical fiber may have multiplexed multiple wavelengths; and the multiple input channels support simultaneous reception of multi-wavelength signals from different terminal devices (such as routers, switches, servers), significantly improving the input capacity of the wavelength division multiplexer, and further processing after convergence through the wavelength division multiplexer, such as filtering and beam combining.

[0023] At least two levels of filtering units are connected in stages, used to perform stage-by-stage filtering on the multi-wavelength multiplexed optical signals input by the multiple input channels, and output multi-wavelength stage-by-stage filtered signals.

[0024] Preferably, the filtering unit separates or screens the input multi-wavelength multiplexed optical signals by wavelength selective filtering devices (such as fiber Bragg gratings, thin film filters, arrayed waveguide gratings, etc.), that is, allows specific wavelength optical signals to pass through and suppresses other wavelength signals, and single filtering level processes wide-band mixed signals, which requires high complexity filtering devices, which may cause high insertion loss (such as multiple reflection / coupling loss) and insufficient wavelength isolation (adjacent wavelength signal crosstalk); the multi-stage filtering unit processes by stages and granularity, decomposes complex filtering tasks, and each stage focuses on coarse screening or fine adjustment of a specific wavelength interval, thereby reducing the pressure on single device and improving overall performance (such as reducing insertion loss and improving isolation).

[0025] Preferably, the two-stage filter unit is connected step by step for step-by-step filtering of the multi-wavelength multiplexed optical signal input by the plurality of input channels. Specifically, the first-stage filter unit uses a wide-band filter device (such as a coarse wavelength division multiplexer CWDM filter) to perform low-resolution filtering on the input signal, and decomposes the mixed signal into a plurality of wavelength subbands to reduce the degree of signal mixing and reduce the cumulative insertion loss in multi-stage processing; the second-stage filter unit uses a narrow-band filter device (such as a dense wavelength division multiplexer DWDM filter, a fiber Bragg grating) to perform high-resolution screening on the wavelength subband to extract a single wavelength or narrowband signal, that is, after the multi-wavelength signal enters from the input port, it is first subjected to coarse separation by the first-stage filter unit to output a plurality of wavelength subband signals; the subband signal then enters the second-stage filter unit to be further decomposed into a single wavelength or narrowband signal, and finally output a multi-wavelength step-by-step filtered signal (such as a wavelength sequence after each stage of filtering), thereby realizing wavelength-level accurate separation and meeting the requirement of high isolation.

[0026] An output port is configured to fit the multi-wavelength step-by-step filtered signal to obtain a combined multiplexed optical signal.

[0027] Preferably, the output port is a signal outlet hub of the wavelength division multiplexer, which is configured to recombine the discrete wavelength signals or subband signals output by the multi-stage filter unit into a single multi-wavelength multiplexed optical signal (i.e., a combined multiplexed optical signal) through an optical device for transmission in a single optical fiber; the output port is also configured to fit the multi-wavelength step-by-step filtered signal, that is, to calibrate and match the optical parameters of the signals output by the multi-stage filtering to ensure that the signal quality is not damaged during combining, specifically including power equalization (adjusting the optical power of each wavelength signal to avoid strong signals suppressing weak signals), phase synchronization (compensating for the phase difference generated by different wavelength signals during filtering), and mode matching (ensuring that the spot patterns of each wavelength signal are consistent to reduce mode mismatch loss during combining), and finally obtaining a combined multiplexed optical signal, wherein the key device for combining is an optical coupler / combiner, and the common types and working mechanisms are shown in Table 1: Table 1 Optical coupler / combiner data table Device type Working principle Typical application scenarios Fused-taper fiber coupler Multiple fibers are fused by the fused-taper process, and multiple wavelength signals are mixed by evanescent field coupling, with low insertion loss (<0.5 dB) Coarse wavelength division multiplexing (CWDM) system, low-cost scenario Arrayed waveguide grating (AWG) Different wavelength signals are focused to the same output port by using the phase delay characteristics of the waveguide array, supporting high-density wavelength beam combining (such as 80 waves or more) Dense wavelength division multiplexing (DWDM) system, long-distance transmission Thin-film filter (TFF) beam combiner Based on the light reflection / transmission characteristics of multilayer dielectric films, the beam is combined layer by layer (such as first combining λ1+λ2, and then combining λ3+ the previous two) Medium-scale wavelength beam combining, flexible configuration scenario Further, the low-insertion-loss wavelength division multiplexer further comprises a plurality of narrowband filters in each of the at least two-stage filter units, wherein the plurality of narrowband filters correspond to the plurality of input channels and respectively receive the multiplexed optical signal of the corresponding channel.

[0028] Preferably, the entire filter module of the low insertion loss wavelength division multiplexer is composed of multiple stages (such as 2 stages, 3 stages, etc.) of filter units connected in series, each stage of filter unit undertakes different stage of filtering task (such as coarse filtering, fine filtering), and the fine separation or multiplexing of the multi-wavelength signal is realized through step-by-step processing. A narrowband filter corresponding to the number of input channels is integrated in each filter unit. For example, if there are N input channels at the input port, there are at least N narrowband filters in each stage of filter unit, wherein N is a positive integer. The narrowband filter is an optical device that only allows light signals of a specific wavelength range to pass through, and has high selectivity, such as thin film filter, fiber Bragg grating, etc. The multi-wavelength multiplexed optical signal transmitted by each input channel is directly connected to the corresponding numbered narrowband filter, ensuring that the signals of each channel do not interfere with each other during the filtering process and maintaining the independence of the signals.

[0029] Further, the low insertion loss wavelength division multiplexer further comprises: if the at least two stages of filter units comprise a first stage of filter units and a second stage of filter units; filtering the multi-wavelength multiplexed optical signal input by the plurality of input channels according to the first stage of filter units to obtain a multi-wavelength first stage of filter signal; inputting the multi-wavelength first stage of filter signal into the second stage of filter units for filtering to obtain a multi-wavelength second stage of filter signal; and outputting the multi-wavelength second stage of filter signal as a multi-wavelength step-by-step filter signal.

[0030] Preferably, at least two stages of filter units (such as a first stage of filter units and a second stage of filter units) are used to process the multi-wavelength multiplexed optical signal step by step to realize the fine separation or multiplexing of the optical signal. Specifically, the first stage of filter units uses a wide spectrum or medium precision narrowband filter to preliminarily filter the input multi-wavelength multiplexed signal, allows the optical signal of the target wavelength range to pass through, and filters out part of the stray light or interference signal deviating from the target wavelength, and outputs the main target wavelength in each channel signal, i.e. the multi-wavelength first stage of filter signal. The second stage of filter units uses a narrowband filter with narrow bandwidth and high selectivity to perform secondary filtering on the multi-wavelength first stage of filter signal output by the first stage of filter units, allowing the target wavelength to pass through and filtering out other wavelengths of interference to the maximum, and outputting the highly purified target wavelength in each channel signal, i.e. the multi-wavelength second stage of filter signal, and outputting it as a multi-wavelength step-by-step filter signal, which is a pure wavelength signal after two stages of filtering, thereby reducing the insertion loss and crosstalk and improving the filtering accuracy and reliability.

[0031] Further, the low insertion loss wavelength division multiplexer further comprises a filter granularity control unit connected with the at least two filter units; the filter granularity control unit is configured to set at least two filter granularities according to the filter stages of the at least two filter units, and configure filter parameters of the at least two filter units according to the at least two filter granularities; each filter granularity comprises corresponding filter parameters, and the filter parameters comprise a bandwidth, a passband center wavelength, a sideband rejection ratio and an insertion loss threshold.

[0032] Preferably, the filter granularity control unit dynamically adjusts the filter precision (granularity) and parameters by matching the filter unit stages, so as to balance the wavelength separation precision of the optical signal and the transmission loss, wherein the filter granularity refers to the filtering precision of the filter on the wavelength of the optical signal, each filter granularity comprises corresponding filter parameters, and the filter parameters comprise a bandwidth, a passband center wavelength, a sideband rejection ratio and an insertion loss threshold. Specifically, the bandwidth refers to the wavelength range (such as a center wavelength ± 50 GHz) allowed to pass through the filter, a wider bandwidth (such as 100 GHz) is set in the first stage (coarse granularity) to ensure that the target wavelength signal passes through completely, and a narrower bandwidth (such as 50 GHz) is set in the second stage (fine granularity) to allow only the target wavelength and signals within a very narrow range to pass through; the passband center wavelength refers to the center wavelength of the filter passband, and the center wavelengths of the filter units need to be strictly aligned with the target wavelength to ensure that the signal does not deviate from the target channel in the multi-stage filtering; the sideband rejection ratio refers to the suppression ability of the filter on the wavelengths outside the passband, and the greater the value, the better the suppression effect, the sideband rejection ratio of the first stage is lower (such as 20 dB), and the sideband rejection ratio of the second stage is higher (such as 35 dB); the insertion loss threshold refers to the upper limit of the power loss of the filter on the optical signal, and the smaller the value, the lower the loss, the first stage allows a higher insertion loss threshold (such as 1.5 dB), and the second stage sets a lower insertion loss threshold (such as 1.0 dB).

[0033] Preferably, the filtering granularity control unit is directly connected with at least two levels of filter units (such as a first level and a second level), and dynamically configures filtering parameters of each level of filter unit according to a preset filtering level, and sets different granularities (such as a first level of coarse granularity and a second level of fine granularity) through hierarchical setting, so as to reduce the insertion loss of each level of filter as much as possible while ensuring the wavelength separation accuracy, and realize the dual goals of high-precision filtering and low-loss transmission; the filtering granularity control unit is configured to set at least two filtering granularities according to the filtering level of the at least two levels of filter units, and configure filtering parameters of the at least two levels of filter units according to the at least two filtering granularities, that is, if the first level and the second level of filter units are included (a total of two levels), the filtering granularity control unit needs to set at least two different filtering granularities (such as granularity A and granularity B) corresponding to different levels of filtering requirements, so that the first level of filter unit adopts a relatively coarse granularity (such as a relatively wide bandwidth) to preliminarily screen the multi-wavelength signal, and the second level of filter unit adopts a relatively fine granularity (such as a relatively narrow bandwidth) to further finely filter the signal output by the first level, so as to ensure that the wavelength accuracy meets the transmission requirements.

[0034] Further, the low-insertion-loss wavelength division multiplexer further includes an insertion loss balancing unit arranged between the at least two levels of filter units, and the insertion loss balancing unit is configured to detect an insertion loss index corresponding to a previous level of filter unit, the insertion loss index including an insertion loss value, a bandwidth offset, and a center wavelength drift; and the insertion loss balancing unit is configured to perform insertion loss balancing compensation on filtering parameters of a next level of filter unit according to the insertion loss index.

[0035] Preferably, in the multi-level filtering module, the optical signal introduces a certain insertion loss (insertion loss) after each level of filtering, and may be accompanied by a bandwidth offset or a center wavelength drift, which may be accumulated level by level, resulting in power attenuation or wavelength misalignment of the final output signal, affecting the communication quality. Then, the insertion loss balancing unit is introduced between the two levels of filter units to monitor the deviation of the previous level and dynamically adjust the parameters of the next level, so as to realize error compensation. Specifically, the insertion loss balancing unit first performs real-time detection on the actual performance of the previous level of filter unit to obtain the insertion loss index, including an insertion loss value (energy loss of the optical signal after passing through the previous level of filter), a bandwidth offset (deviation of the actual passband width of the previous level of filter from the designed value), and a center wavelength drift (amplitude of the deviation of the passband center wavelength of the previous level of filter from the target value); then, the insertion loss balancing unit dynamically adjusts the filtering parameters of the next level of filter unit according to the deviation detected by the previous level, so as to compensate for the error introduced by the previous level, including insertion loss compensation (reducing the insertion loss threshold of the next level of filter unit), bandwidth offset compensation (narrowing the bandwidth parameter of the next level of filter unit), and center wavelength drift compensation (dynamically adjusting the passband center wavelength of the next level of filter unit to offset in the opposite direction to offset the error of the previous level), so as to finally realize overall high performance through the compensation of the next level, and balance the cost and the index.

[0036] Further, the low insertion loss wavelength division multiplexer further comprises that the input end of the output port comprises a fitting module; the multi-wavelength step-by-step filtered signal is fitted according to the fitting module to obtain a combined multiplexed optical signal, and the combined multiplexed optical signal is output through the output port.

[0037] Preferably, the fitting module is a signal processing unit integrated in the front end of the output port, which is used for waveform fitting reconstruction of the optical signal after multi-stage filtering, to ensure that the signal can still maintain good transmission quality after filtering. Specifically, the input signal is a multiplexed optical signal containing multiple wavelengths, and after being processed by at least two filtering units, the signal of each wavelength may produce waveform distortion (signal edge becomes slow, amplitude attenuation or phase shift), noise introduction (accumulative noise) and wavelength crosstalk (signals of adjacent wavelengths produce interference). The fitting module compensates the waveform distortion caused by filtering (such as raised cosine filtering, equalization filtering, etc.) through an algorithm, restores the original shape of the signal; adjusts the power of each wavelength signal to make the amplitudes of signals of different wavelengths consistent; reduces noise through filtering or digital signal processing (DSP) technology to improve the signal-to-noise ratio; ensures the center frequency of each wavelength signal to be accurate to avoid wavelength shift caused by filtering; and then recombines the multi-wavelength signal after fitting into a multiplexed optical signal for transmission in a single optical fiber.

[0038] Further, the low insertion loss wavelength division multiplexer further comprises that the multiple input channels of the input port are arranged according to a preset wavelength interval, and the preset wavelength interval is 100 GHz or 50 GHz.

[0039] Preferably, the input port of the low insertion loss wavelength division multiplexer comprises multiple independent input channels, and the multiple input channels are arranged according to a preset wavelength interval, wherein the wavelength interval refers to the difference between the center wavelengths of the optical signals carried by adjacent input channels, and the unit is frequency (GHz) or wavelength (nm). The preset wavelength interval is 100 GHz or 50 GHz, which represents a standard wavelength interval commonly used in optical communication, corresponding to different spectral resource allocation densities. The frequency difference between adjacent wavelengths of the 100 GHz interval is 100 GHz, which corresponds to a wavelength interval of about 0.8 nm. The frequency difference between adjacent wavelengths of the 50 GHz interval is 50 GHz, which corresponds to a wavelength interval of about 0.4 nm, and the spectral utilization rate is higher.

[0040] The embodiment of the present application also provides a control method of a low insertion loss wavelength division multiplexer, as shown in Figure 1 The method comprises: Step S100, according to the input port of the low insertion loss wavelength division multiplexer, obtaining the multi-wavelength multiplexed signal received by the multiple input channels; Step S200, presetting multiple filter granularities for the multi-stage filter unit of the low insertion loss wavelength division multiplexer, and performing multi-stage filtering on the multi-wavelength multiplexed signal according to the multiple filter granularities, and outputting multi-wavelength step-by-step filtered signal; Step S300, fitting the multi-wavelength step-by-step filtered signal according to the output port of the low insertion loss wavelength division multiplexer, and obtaining the combined multiplexed optical signal.

[0041] Preferably, the multiple input channels of the input port of the low insertion loss wavelength division multiplexer receive the multi-wavelength multiplexed optical signal through the optical coupler or the optical splitter, ensuring that the multi-wavelength signal enters the wavelength division multiplexer completely and without distortion. Then, according to the number of filter units, multiple filter granularities are preset for the multi-stage filter unit of the low insertion loss wavelength division multiplexer, and then the multi-wavelength multiplexed signal is filtered according to the multiple filter granularities. Specifically, the multi-wavelength signal of each input channel enters the corresponding first-stage filter unit, the filter allows the target wavelength group to pass according to the coarse granularity parameter, filters out the obvious non-target wavelength, and outputs the multi-wavelength first-stage filtered signal; then the sub-band signal output by the first stage enters the second-stage filter unit, and the corresponding fine granularity filter is accessed, the filter further screens according to the fine granularity parameter, and only allows single wavelength to pass, and outputs the multi-wavelength step-by-step filtered signal. Finally, the multi-wavelength step-by-step filtered signal is fitted according to the output port of the low insertion loss wavelength division multiplexer, including power balancing, waveform reconstruction and phase synchronization, and finally the combined multiplexed optical signal is output, while ensuring low insertion loss, high precision and flexibility.

[0042] Further, a control method of a low insertion loss wavelength division multiplexer further comprises: collecting the insertion loss indicators of each stage filter unit in the multi-stage filter unit in real time, the insertion loss indicators are obtained by weight calculation on the insertion loss value, bandwidth offset and center wavelength drift; starting the insertion loss balancing unit of the low insertion loss wavelength division multiplexer, and the insertion loss balancing unit compensates the filter parameters of the next stage filter unit according to the insertion loss indicators.

[0043] Preferably, the insertion loss value, bandwidth offset and center wavelength drift of each stage filter unit in the multi-stage filter unit are collected in real time, and then different weights (such as insertion loss value 50%, bandwidth offset 30% and center wavelength drift 20%) are set for the three indicators according to the requirements of different application scenarios (such as that high-speed transmission is more sensitive to center wavelength drift, and bandwidth offset affects channel isolation), and then the three indicators are weighted and calculated to obtain the insertion loss indicators, so as to evaluate the performance degradation of the filter unit in real time. Then, the insertion loss balancing unit of the low insertion loss wavelength division multiplexer is started, and the filter parameters of the next stage filter unit are compensated according to the insertion loss indicators, as shown in Table 2: Table 2: Insertion loss indicator and insertion loss compensation correspondence table Insertion loss index Compensation by the post-stage filter unit High insertion loss value Increase the gain of the post-stage filter unit (such as reverse compensation by an adjustable optical attenuator); optimize the steepness of the filter curve and reduce the in-band loss Bandwidth offset Adjust the passband width of the post-stage filter unit (such as widening or narrowing the bandwidth by an adjustable filter); match the bandwidth after the pre-stage offset to avoid channel crosstalk Center wavelength drift Fine-tune the center wavelength of the post-stage filter unit (such as temperature control or voltage tuning); align the center wavelengths of the passbands of the pre-stage and post-stage to ensure smooth signal transmission Further, the control method of the low insertion loss wavelength division multiplexer further comprises: obtaining a channel interval of the low insertion loss wavelength division multiplexer; determining a range of each filter parameter according to the channel interval of the low insertion loss wavelength division multiplexer, wherein the filter parameter comprises a bandwidth, a passband center wavelength, a sideband suppression ratio and an insertion loss threshold; and dividing the number of the multi-stage filter units to obtain a plurality of filter granularities in the range of each filter parameter.

[0044] Preferably, the channel interval of the low insertion loss wavelength division multiplexer, i.e. the difference between the center frequencies of adjacent optical channels, is obtained, and a common value is 100 GHz (about 0.8 nm) or 50 GHz (about 0.4 nm), and then the range of each filter parameter (bandwidth, passband center wavelength, sideband suppression ratio and insertion loss threshold) is determined according to the channel interval of the low insertion loss wavelength division multiplexer, for example, the bandwidth usually needs to be less than 50% of the channel interval (such as 50 GHz interval corresponding to a bandwidth ≤ 0.2 nm) to avoid adjacent channel crosstalk; the tolerance usually needs to be within 5% of the channel interval (such as ± 0.02 nm) to ensure that the signal is located at the center of the passband; the sideband suppression ratio is inversely proportional to the channel interval, the smaller the interval, the higher the requirement (such as 50 GHz interval ≥ 30 dB, 100 GHz interval ≥ 25 dB); the insertion loss threshold has no direct correlation with the channel interval, but the loss of each stage needs to be controlled (such as single stage ≤ 0.5 dB) when multi-stage filtering to avoid excessive accumulation. Finally, different precision filter granularities are allocated according to the number of multi-stage filter units in the range of each filter parameter, for example, the first stage (coarse granularity) parameter range is wider, quickly separates the target wavelength group (such as bandwidth 0.4 nm, sideband suppression ratio 25 dB), and the second stage (fine granularity) parameter range is narrowed, accurately locates a single wavelength (such as bandwidth 0.1 nm, sideband suppression ratio 35 dB).

[0045] Although the low insertion loss wavelength division multiplexer according to the embodiments of the present application is variously referred to in the present application, each unit included therein is only divided according to functional logic, but is not limited to the above division, as long as the corresponding function can be realized; in addition, the specific names of each functional unit are only for the convenience of mutual differentiation, and do not limit the protection scope of the present application.

[0046] The above specific embodiments do not constitute a limitation on the protection scope of the present application. It should be understood by those skilled in the art that various modifications, combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A low insertion loss wavelength division multiplexer characterized by comprising: The low insertion loss wavelength division multiplexer comprises: An input port comprising a plurality of input channels for receiving a multi-wavelength multiplexed optical signal; At least two stages of filter units connected in stages for filtering the multi-wavelength multiplexed optical signal input by the plurality of input channels in stages to output a multi-wavelength filtered signal in stages; An output port for fitting the multi-wavelength filtered signal in stages to obtain a combined multiplexed optical signal.

2. The low insertion loss wavelength division multiplexer of claim 1, wherein, Each stage of filter units in the at least two stages of filter units comprises a plurality of narrowband filters corresponding to the plurality of input channels and respectively receiving the multiplexed optical signal of the corresponding channel.

3. The low insertion loss wavelength division multiplexer of claim 1, wherein, If the at least two stages of filter units comprise a first stage of filter units and a second stage of filter units; According to the first stage of filter units, the multi-wavelength multiplexed optical signal input by the plurality of input channels is filtered to obtain a multi-wavelength first stage of filtered signal, and the multi-wavelength first stage of filtered signal is input into the second stage of filter units for filtering to obtain a multi-wavelength second stage of filtered signal; The multi-wavelength second stage of filtered signal is output as a multi-wavelength filtered signal in stages.

4. The low insertion loss wavelength division multiplexer of claim 3, wherein, The low insertion loss wavelength division multiplexer comprises a filter granularity control unit connected with the at least two stages of filter units; The filter granularity control unit is configured to set at least two filter granularities according to the filter stages of the at least two stages of filter units, and configure filter parameters of the at least two stages of filter units according to the at least two filter granularities; Each filter granularity comprises corresponding filter parameters, and the filter parameters comprise a bandwidth, a passband center wavelength, a sideband suppression ratio, and an insertion loss threshold.

5. The low insertion loss wavelength division multiplexer of claim 1, wherein, An insertion loss equalization unit is arranged between the at least two stages of filter units, and the insertion loss equalization unit is configured to detect an insertion loss index corresponding to a previous stage of filter units, wherein the insertion loss index comprises an insertion loss value, a bandwidth offset, and a center wavelength drift; According to the insertion loss index, the filter parameters of a next stage of filter units are compensated for insertion loss equalization.

6. The low insertion loss wavelength division multiplexer of claim 5, wherein, The input end of the output port comprises a fitting module; According to the fitting module, the multi-wavelength filtered signal in stages is fitted to obtain a combined multiplexed optical signal, and the combined multiplexed optical signal is output through the output port.

7. The low insertion loss wavelength division multiplexer of claim 1, wherein, The plurality of input channels of the input port are arranged according to a preset wavelength interval, and the preset wavelength interval is 100 GHz or 50 GHz.

8. A control method of a low insertion loss wavelength division multiplexer, characterized by, The control method is applied to the low insertion loss wavelength division multiplexer in any one of claims 1-7, and the method comprises: According to the input port of the low insertion loss wavelength division multiplexer, a multi-wavelength multiplexed signal received by a plurality of input channels is obtained; A plurality of filter granularities are preset for a plurality of stages of filter units of the low insertion loss wavelength division multiplexer, and the multi-wavelength multiplexed signal is filtered in multiple stages according to the plurality of filter granularities to output a multi-wavelength filtered signal in stages; According to the output port of the low insertion loss wavelength division multiplexer, the multi-wavelength filtered signal in stages is fitted to obtain a combined multiplexed optical signal.

9. The control method according to claim 8, characterized by, The method for filtering the multi-wavelength multiplexed signal according to the plurality of filter granularities comprises: Real-time acquisition of the insertion loss index of each stage filter unit in the multi-stage filter unit, the insertion loss index is obtained by weight calculation on the insertion loss value, bandwidth offset, center wavelength drift; Start the insertion loss equalization unit of the low insertion loss wavelength division multiplexer, the insertion loss equalization unit compensates the filter parameters of the next stage filter unit according to the insertion loss index.

10. The control method according to claim 8, characterized by, A plurality of filter granularities are preset for the multi-stage filter unit of the low insertion loss wavelength division multiplexer, and the method comprises: Obtaining the channel spacing of the low insertion loss wavelength division multiplexer; According to the channel spacing of the low insertion loss wavelength division multiplexer, the range of each filter parameter is determined, wherein the filter parameters include bandwidth, passband center wavelength, sideband suppression ratio and insertion loss threshold; Under the range of each filter parameter, the number of multi-stage filter units is divided to obtain a plurality of filter granularities.

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