Polarization insensitive four-channel four-wavelength selective switch

Abstract

The application discloses a polarization-insensitive four-channel four-wavelength selection switch and relates to the technical field of optical communication. The polarization-insensitive four-channel four-wavelength selection switch comprises a shell, an input assembly, a polarization processing assembly, a light splitting assembly, a wavelength selection assembly and a light combination output assembly which are sequentially connected in an optical path and are arranged in the shell, so that the input assembly can stably receive multiple optical signals; the polarization processing assembly unifies the optical signals into a single TE polarization state through polarization processing units on four parallel buried optical waveguide channels; the light splitting assembly splits the four optical signals into 16 sub-signals through four optical couplers and light splitting processing units and realizes power consistency through a channel power equalizer; the wavelength selection assembly selects independent wavelengths through 16 MEMS tunable filters integrated in a 4*4 matrix; and the light combination output assembly combines four wavelengths in each channel into a multi-wavelength signal output through four arrayed waveguide grating light combiners.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, specifically to a polarization-insensitive four-channel four-wavelength selection switch. Background Technology

[0002] In dense wavelength division multiplexing (DWDM) systems for optical communication, the wavelength selective switch (WSS) is a core component for enabling flexible scheduling of wavelength resources and dynamic configuration of transmission links in optical networks. This is driven by the surging demand for bandwidth density and scheduling flexibility in optical transmission from scenarios such as 5G communication and data center interconnection.

[0003] In current optical communication networks, wavelength selective switches are core components for achieving flexible wavelength scheduling and network resource optimization, and their polarization insensitivity is key to ensuring signal transmission stability.

[0004] The existing authorized invention patent "A polarization-insensitive dual-channel dual-wavelength selection switch" (patent number: CN113759469B, application number: 202111115974.0) discloses a dual-channel scheme based on polarization beam splitting and wavelength filtering. It eliminates polarization sensitivity through a polarization processing module (including a polarization beam splitter and a half-wave plate), and then realizes independent switching of dual-wavelength signals through a dual-channel wavelength selection unit, thus solving the signal loss problem caused by polarization sensitivity in traditional WSS.

[0005] However, with the increasing bandwidth demands of scenarios such as 5G communication and data center interconnection, existing dual-channel dual-wavelength solutions have significant limitations: First, the number of channels is only 2, which cannot meet the parallel scheduling requirements of multiple users and multiple services. If multiple devices are cascaded to expand the channels, it will lead to an increase in system size and cost. Second, the number of wavelengths processed is limited, with a single device only supporting the independent selection of 2 wavelengths, making it difficult to adapt to the flexible configuration of multi-wavelength signals in dense wavelength division multiplexing (DWDM) systems. In addition, some existing multi-channel expansion solutions are prone to problems such as increased polarization crosstalk and increased insertion loss (usually >5dB) when increasing the number of channels, resulting in a decrease in signal transmission quality. Summary of the Invention

[0006] The purpose of this invention is to provide a polarization-insensitive four-channel four-wavelength selective switch to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a polarization-insensitive four-channel four-wavelength selection switch, comprising: a housing, and an input component, a polarization processing component, a beam splitting component, a wavelength selection component, and a beam combining output component installed inside the housing and connected in sequence by optical paths; The input component is used to receive multiple input optical signals; The polarization processing component includes an integrated quartz substrate, multiple polarization processing units, and a microlens array. The multiple polarization processing units are integrated on the surface of the integrated quartz substrate and are used to unify the polarization state of each input optical signal to a predetermined polarization state. The microlens array is coupled to the optical path of the beam splitter. The wavelength selection component includes an integrated substrate and a plurality of tunable filters disposed thereon, for independently selecting wavelengths for multiple sub-signals; The light combining output component includes a light combining shell, an input interface, a light combining processing unit, a collaborative output connection component, and a single output connection component. The light combining processing unit combines wavelength-selected sub-signals into multiple output signals according to wavelength, and outputs them to the outside through the collaborative output connection component and the single output connection component as needed.

[0008] Preferably, the polarization processing unit outputs two sets of optical paths from its side, and the side ends of the two sets of optical paths are connected to a half-wave plate. The side ends of the half-wave plate are connected to an output channel, and a coupling loss protection layer is laid on the outside of the output channel.

[0009] Preferably, the input component includes four sets of polarization-maintaining optical fibers arranged in parallel, and the output ends of the polarization-maintaining optical fibers are respectively adapted and connected to the output channels.

[0010] Preferably, the polarization processing component is an integrated polarization processing chip. The integrated quartz substrate integrates four sets of polarization beam splitters and four half-wave plates. The spacing between adjacent polarization beam splitters is the same as the spacing between multiple polarization processing units. The half-wave plates are set at a 45° angle to the reflected light path of the polarization beam splitters.

[0011] Preferably, the microlens array is disposed at the output end of the integrated polarization processing chip, and the array microlenses of the microlens array correspond to the output optical path of the polarization processing unit, and are used to couple the optical signal to the optical coupler.

[0012] Preferably, the beam splitting component includes four optical couplers, a beam splitting processing unit, and a channel power equalizer. Each optical coupler corresponds to one beam splitting path on the side of the beam splitting processing unit. The connection end of the beam splitting processing unit and the channel power equalizer is connected to a 4×4-channel output terminal. The beam splitting processing unit splits each polarized optical signal into multiple sub-signals.

[0013] Preferably, the plurality of tunable filters are MEMS tunable filters and are integrated in a matrix on the same ceramic substrate. A receiving end is connected to the side of the ceramic substrate, and the receiving end is connected to the output end of the input optical path. A synchronous driving circuit is installed inside the ceramic substrate. The synchronous driving circuit is used to control the MEMS tunable filters. The synchronous driving circuit is a control circuit, and the control circuit configures the wavelength selection rules in real time through a preset wavelength channel mapping table.

[0014] Preferably, the light combining output component includes four arrayed waveguide grating light combiners, which are disposed inside the light combining housing. The channels of each arrayed waveguide grating light combiner are spaced apart. The output end of each arrayed waveguide grating light combiner is provided with a power flattening circuit, which is used to stabilize the output power fluctuation. The output end of the power flattening circuit is connected to a cooperative output connection component and a single output connection component.

[0015] Preferably, a heat dissipation control terminal is installed on the side of the housing, and multiple control communication terminals are installed on the bottom of the housing.

[0016] Preferably, the left end of the housing is provided with an output polarization-maintaining fiber optic interface.

[0017] Compared with the prior art, the beneficial effects of the present invention are: In this invention, a housing, an input component, a polarization processing component, a beam splitting component, a wavelength selection component, and a beam combining output component are used. The input component stably receives multiple optical signals; the polarization processing component employs an integrated polarization processing chip based on planar waveguide technology, using polarization processing units integrated on four parallel buried waveguide channels to unify the input optical signals into a single TE polarization state; the beam splitting component uses four optical couplers and beam splitting processing units to hierarchically split the four optical signals into 16 sub-signals, and achieves power consistency through channel power equalizers; the wavelength selection component integrates 16 MEMS tunable filters in a 4×4 matrix on an aluminum nitride ceramic substrate to independently select the wavelengths of the 16 sub-signals; the beam combining output component uses four arrayed waveguide grating beam combiners to combine the four wavelengths of each channel into a single multi-wavelength signal, which is then output through a power flattening circuit and either a coordinated output connection component or a single output connection component. This switch enables four-channel, four-wavelength scheduling with insertion loss ≤3dB, polarization-dependent loss ≤0.5dB, and polarization crosstalk ≤-40dB, meeting the requirements of high-capacity optical communication networks. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the main view of a polarization-insensitive four-channel four-wavelength selective switch according to the present invention. Figure 2This is a schematic diagram of the internal cross-sectional structure of the main body of a polarization-insensitive four-channel four-wavelength selective switch according to the present invention. Figure 3 This is a schematic diagram of the polarization processing component structure in a polarization-insensitive four-channel four-wavelength selective switch of the present invention. Figure 4 This is a schematic diagram of the optical combining output component in a polarization-insensitive four-channel four-wavelength selective switch of the present invention. Figure 5 This is a schematic diagram of the structure of the beam splitting component in a polarization-insensitive four-channel four-wavelength selective switch of the present invention; Figure 6 This is a schematic diagram of a portion of the flow structure of the wavelength selection component in a polarization-insensitive four-channel four-wavelength selection switch of the present invention. Figure 7 This is a schematic diagram of the four-channel, four-wavelength flow structure in a polarization-insensitive four-channel, four-wavelength selective switch of the present invention. Figure 8 This is a schematic diagram of the wavelength selection component in a polarization-insensitive four-channel four-wavelength selection switch of the present invention. Figure 9 This is a schematic diagram of the beam splitting component in a polarization-insensitive four-channel four-wavelength selective switch of the present invention.

[0019] In the diagram: 100, Housing; 200, Output polarization-maintaining fiber optic interface; 300, Heat dissipation control terminal; 400, Control and communication terminal; 500, Polarization processing component; 501, Integrated quartz substrate; 502, Polarization processing unit; 504, Output channel; 505, Bent waveguide; 506, Half-wave plate; 507, Microlens array; 508, Polarization beam splitter; 600, Beam splitting component; 601, Optical coupler; 602, Beam splitting processing unit; 603, 4 × Four-way output terminal; 604, Channel power equalizer; 605, Beam splitting path; 700, Wavelength selection component; 701, Ceramic substrate; 702, Tunable filter; 703, Synchronous drive circuit; 704, Receiver; 800, Beam combining output component; 801, Input interface; 802, Cooperative output connection component; 803, Single output connection component; 804, Power flattening circuit; 805, Beam combining housing; 806, Arrayed waveguide grating beam combiner. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To address the limitations of existing polarization-insensitive dual-channel dual-wavelength selective switches, such as limited channel count (only 2 channels) and wavelength processing capability (only 2 wavelengths), which fail to meet the high-capacity scheduling requirements of optical communication networks and are prone to polarization crosstalk and increased insertion loss when expanding channels, this invention provides a polarization-insensitive four-channel four-wavelength selective switch. (Refer to...) Figure 1 and Figure 2 As shown: It includes a housing 100 and an input component, a polarization processing component 500, a beam splitting component 600, a wavelength selection component 700, and a beam combining output component 800 installed inside, which are connected in sequence by optical paths. The housing 100 is an external frame and internal protective carrier, made of a composite material of aluminum alloy and engineering plastic (for lightweighting and electromagnetic shielding). The input component is used to stably receive multiple input optical signals and transmit them to subsequent components (i.e., polarization processing component 500, beam splitting component 600, wavelength selection component 700, and beam combining output component 800). The polarization processing component 500 is used to unify the polarization state of each input optical signal to a single preset polarization state. Then, the beam splitting component 600 evenly splits each polarization-processed single optical signal into multiple parallel sub-signals, ensuring that the power of each sub-signal is consistent. Next, the wavelength selection component 700 performs independent wavelength selection on each sub-signal after beam splitting, filtering out the target wavelength required for each channel. Finally, the beam combining output component 800 combines the four target wavelength sub-signals corresponding to each channel into a main output signal containing multiple target wavelengths, and stably transmits it to the external optical network.

[0022] Preferably, in the specific scheme of the polarization processing component 500, according to Figure 2 and Figure 3 As shown, the polarization processing component 500 is an integrated polarization processing chip based on planar optical waveguide technology. Its core physical foundation is an integrated quartz substrate 501 made of high-purity fused silica material, which serves as a common platform for all optical components. On the integrated quartz substrate 501, four parallel buried optical waveguide channels are first formed in one step through photolithography and reactive ion etching processes. The photolithography and reactive ion etching processes can ensure that the consistency deviation of the physical dimensions (such as waveguide width and height) and optical characteristics (such as refractive index distribution and propagation constant) of the four buried optical waveguide channels is controlled within a very small range, fundamentally guaranteeing the synchronization and uniformity of the four-channel signal processing.

[0023] On each buried optical waveguide channel, thin film deposition and microfabrication processes are used to sequentially integrate functional units to form a corresponding polarization processing unit 502.

[0024] Each polarization processing unit 502 is designed with cascade integration, sequentially including a polarization beamsplitter 508 and a half-wave plate 506 along the optical waveguide propagation path. Specifically, the polarization beamsplitter 508 is implemented based on an asymmetric Y-branch or directional coupler structure, utilizing the different propagation constants of different polarization states (i.e., TE polarized light corresponds to s-rays, and TM polarized light corresponds to p-rays) in the waveguide to achieve polarization separation. In the polarization beamsplitter based on the asymmetric Y-branch or directional coupler, polarization separation is typically achieved using the sidewall interface. In this case, the electric field direction of the TE mode (electric field parallel to the substrate) is perpendicular to the incident plane, conforming to the definition of s-rays; the electric field direction of the TM mode (electric field perpendicular to the substrate) is parallel to the incident plane, conforming to the definition of p-rays.

[0025] When an input optical signal containing randomly proportioned p / s polarized light is transmitted through the waveguide to the polarization beamsplitter 508 region, the TE polarized light (s-beam) continues to propagate forward along the original main waveguide channel due to propagation constant matching; while the TM polarized light (p-beam) is coupled into an adjacent curved waveguide 505 and enters the half-wave plate 506 region. The half-wave plate 506 is formed by covering the dedicated curved waveguide 505 with a material with specific birefringence properties (such as a polymer film processed by optical alignment). Its optical axis is precisely set to the propagation path of the TM polarized light in the curved waveguide 505. When the TM polarized light passes through this region, its vibration direction will rotate by 90° under the action of birefringence, and finally be transformed into a polarization state that is completely consistent with the vibration direction of the TE polarized light. Then, it is re-integrated into the output channel 504 of the original main waveguide through a curved waveguide 505 beam combiner structure, and merged with the straight-going TE polarized light. At this point, all optical signals transmitted in the waveguide have been unified into a single TE polarization state, achieving polarization-insensitive preprocessing.

[0026] To further suppress crosstalk between channels that may be caused by high-density integration, a deep trench isolation structure is specially designed between the four adjacent parallel optical waveguide channels. This structure is etched using a deep trench isolation process, with a depth greater than the thickness of the optical waveguide layer. The trenches are filled with light-absorbing materials (such as benzocyclobutene doped with carbon black), which effectively absorbs side light generated by process defects or scattering, ensuring the high independence and signal purity of the four channels. Simultaneously, the polarization extinction ratio of the overall polarization processing unit 502 is greater than 30dB, strongly guaranteeing the thoroughness of polarization uniformity. For input coupling, the input component uses four sets of parallel polarization-maintaining fibers. These fibers are directly connected to the input end face of the integrated quartz substrate 501 through a high-precision V-groove array, and are fixed and refractive index matched using end face refractive index matching adhesive, thereby achieving low-loss, high-stability coupling between the fibers and the chip waveguide. At the output end, the output end face of the integrated quartz substrate 501 is precision polished, where the output light from the four optical waveguide channels is converted from propagation within the confined waveguide to exiting into free space. At this point, the microlens array 506 is precisely fixed to the output end face of the substrate using UV-curable adhesive. The optical axis of each microlens in the array is aligned with the center of the corresponding output waveguide channel. This microlens array 506 is used to collimate the divergent light signal output from the waveguide into a parallel beam, enabling efficient optical path coupling with the optical coupler 601 of the subsequent beam splitter 600. Simultaneously, the microlens array 506 is further calibrated using a slot structure for added stability, ensuring that the collimated light signal is precisely aligned with the entrance of the output channel 504. The output channel 504 employs a quartz capillary structure, with one end connected to the light-emitting surface of the microlens array 506 and the other end extending to connect to the optical coupler 601 of the beam splitter 600. A silicone rubber coupling loss protection layer is laid on the outer side of the output channel 504 to isolate the influence of external vibrations, dust, and other environmental factors on the stability of the optical path.

[0027] During the complete dynamic operation, the four DWDM input optical signals first pass through four sets of polarization-maintaining fibers and are efficiently coupled into the four parallel optical waveguide channels of the integrated quartz substrate 501 via V-grooves. Then, they undergo polarization separation by the polarization beam splitter 508, polarization rotation by the half-wave plate 509, and beam combining in sequence within the waveguide, and are finally all unified into the TE polarization state. After the optical signal with unified polarization is transmitted along the waveguide to the chip output surface, it is immediately collimated into parallel light by the microlens array 506 after exiting into free space and precisely injected into the output channel 504, and then transmitted to the optical coupler 601 of the beam splitter 600. In this process, the four polarization processing units 502 simultaneously complete the above polarization unification operation, jointly realizing the polarization state unification of the four-channel input optical signals. This provides a foundation of optical signals with completely consistent polarization state and extremely low crosstalk for the subsequent beam splitting operation of the beam splitter 600, enabling the entire optical communication system to effectively overcome the polarization state change problem caused by link factors such as fiber bending and temperature fluctuations, significantly reduce polarization-related losses, and thus ensure the transmission stability and low bit error rate performance of long-distance, high-speed optical signals.

[0028] Preferably, based on the scheme description of polarization processing component 500, The beam splitter assembly 600 includes four optical couplers 601, a beam splitting processing unit 602, and a channel power equalizer 604. Each optical coupler 601 corresponds to one beam splitting path 605 on the side of the beam splitting processing unit 602. The connection between the beam splitting processing unit 602 and the channel power equalizer 604 is connected to a 4×4-channel output terminal 603. The beam splitting processing unit 602 splits each polarized optical signal into multiple sub-signals. The multiple beam splitting paths 605 adopt a quartz capillary structure. One end of the path is bonded and fixed to the output end of the optical beam splitter 601, and the other end extends to the beam splitting processing unit 602. Its function is to independently transmit the optical signals coupled and distributed by the optical couplers 601 to the corresponding beam splitting processing unit 602, avoiding crosstalk between paths.

[0029] The beam splitting unit 602 employs four independent fixed-gain optical beamsplitters, each with its input terminal connected to a beam splitting path 605. It's important to note that firstly, the four optical signals from the polarization processing component 500 are combined into parallel main optical paths via optical coupler 601. Subsequently, each main optical path signal enters a corresponding fixed-gain optical beamsplitter, which is fabricated using a fused biconical tapered process to evenly split the single input optical signal into four sub-signals. Therefore, after passing through the four fixed-gain optical beamsplitters, the four main optical path signals ultimately form 16 sub-signals, each corresponding to one of the 16 independent channels of the subsequent wavelength selection component 700. This hierarchical beam splitting structure, which first splits into four paths and then each path is further split into four, effectively controls beam splitting loss and ensures power consistency among the sub-signals.

[0030] The channel power equalizer 604 independently adjusts the power of the 16 sub-signals output from the beam splitting unit 602, which may have power differences due to process variations. This ensures that the 16 optical signals ultimately input to the wavelength selection component 700 have highly consistent power, thereby achieving extremely low inter-channel insertion loss ripple and excellent stability for the entire switching system. The channel power equalizer 604 is an integrated fixed-gain adjustment module, its core being a 16-channel fixed-gain optical attenuator array. This 16-channel fixed-gain optical attenuator array consists of 16 independent fixed-gain attenuation units, each connected in series with one output sub-signal of the beam splitting unit 602. The fixed-gain attenuation units used in this device have their attenuation determined through precise design during manufacturing, eliminating the need for dynamic electronic control adjustment and avoiding the delays associated with complex closed-loop feedback control. Each fixed-gain attenuation unit can be implemented using an absorptive waveguide structure doped with metal ions or a micro-lens coating at a specific angle. By designing the waveguide length, doping concentration, or reflectivity of the lens coating, the optical signal receives a preset, precise fixed attenuation after passing through the unit, such as a fixed attenuation of 0.5dB or 1.0dB to compensate for the difference in splitting loss in the preceding stage. This fixed-gain design not only simplifies system complexity and reduces power consumption but also avoids the additional noise and reliability issues that might be introduced by electronic control adjustment. The 16 fixed-gain attenuation units are integrated on the same quartz or silicon substrate, forming a compact array structure. The units are isolated by deep trenches or filled with light-absorbing materials to ensure no crosstalk interference between adjacent channels. After adjustment by the channel power equalizer 604, the power difference of the 16 sub-signals is controlled within a very small range, and then precisely transmitted to the 16 tunable filters of the wavelength selection component 700 through the output fiber array, providing a highly consistent optical signal foundation for subsequent wavelength selection stages.

[0031] Further preferably, the four uniformly polarized optical signals (all p-polarized at this time) output by the polarization processing component 500 are precisely transmitted to the input end of the optical coupler 601 of the beam splitter component 600 through the output channel 504. The optical coupler 601 adopts an optical path distribution structure formed by fused biconical tapering process, which evenly splits each input parallel light into four optical signals of similar power through the beam splitting processing unit 602. After the optical signals reach the beam splitting processing unit 602, they enter four independent 1×4 fixed gain optical beam splitters. Each 1×4 optical beam splitter receives a set (i.e., 4 channels) of input optical signals and then evenly splits them into four sub-signals again. Through this hierarchical beam splitting structure of first splitting into four channels and then splitting each channel into four, the four input optical signals are finally converted into 16 sub-signals, which are output in the form of 16 independent optical fibers through the 4×4 output end 603 of the beam splitting processing unit 602.

[0032] An integrated channel power equalizer 604 is located within or at the output of the beam splitting unit 602. This channel power equalizer 604 is a 16-channel fixed-gain optical attenuator array. Due to slight splitting ratio deviations that may exist during the manufacturing process of the four 1×4 optical beam splitters, the initial power of the 16 sub-signals is not entirely consistent. Each fixed-gain attenuation unit of the channel power equalizer 604 is connected in series with the output of each sub-signal. Through a preset, precise fixed attenuation amount (e.g., 0.3dB, 0.5dB, etc.), it performs one-time, passive power compensation for the sub-signals with deviations, thereby controlling the power difference between the 16 sub-signals within a very small range. This fixed-gain design eliminates the need for dynamic electronic control adjustment, avoids complex feedback control systems, simplifies the system structure, reduces power consumption, and improves reliability.

[0033] Finally, the 16 highly consistent sub-signals, precisely compensated by the channel power equalizer 604, are accurately transmitted through 16 independent optical fibers to the inputs of the 16 tunable filters in the wavelength selection component 700, providing a stable and uniform optical signal foundation for subsequent independent wavelength selection. Through the coordinated operation of the aforementioned hierarchical splitting and fixed gain compensation, the entire beam splitter 600 effectively controls inter-channel insertion loss fluctuations, ensuring overall power equalization performance.

[0034] A further preferred embodiment of the wavelength selection component 700 is as follows: Figure 2 and Figure 8 As shown, the wavelength selection component 700 is used to independently select the wavelength of the 16 sub-signals input from the beam splitter 600. Its physical carrier is a highly thermally conductive aluminum nitride ceramic substrate 701. A precise metal wiring layer is fabricated on the surface of the ceramic substrate 701 using a thick-film printing process, connecting the functional units and forming a grid-like heat dissipation path. A serpentine microchannel structure is designed on the back of the substrate, connected to the heat dissipation control terminal 300 of the housing 100, which can quickly dissipate the heat generated during the operation of the MEMS filter, avoiding filter accuracy drift caused by temperature rise. Sixteen independent MEMS tunable filters 702 are integrated in a 4×4 matrix on the aluminum nitride ceramic substrate 701. Each tunable filter 702 receives one sub-signal output from the beam splitter 600. The wavelength adjustment range of the MEMS tunable filters 702 covers 1525-1565nm, with an adjustment accuracy of ±0.01nm. The wavelength switching speed of a single tunable filter 702 is ≤10ms, supporting simultaneous and rapid scheduling of four signals. As an alternative, MEMS tunable filters can also be replaced with liquid crystal tunable filters, with a switching speed of ≤20ms, which is suitable for applications with lower requirements for response speed.

[0035] The ceramic substrate 701 incorporates a synchronous drive circuit 703, which is controlled by the same clock source and used to coordinate the driving timing of the 16 MEMS tunable filters 702. The synchronous drive circuit 703 performs logic adjustment based on a wavelength channel mapping table. The wavelength channel mapping table is as follows: Figure 6 As shown, the system records the current operating wavelength, channel, and priority of each tunable filter 702 in real time. When a wavelength scheduling command is received, specific wavelength configuration parameters are sent to the synchronous drive circuit 703 via the SPI communication interface.

[0036] The synchronous drive circuit 703 performs conflict detection based on the mapping table: if two or more filters are detected requesting to switch to the same wavelength, arbitration is performed according to the preset channel priority rules. For example, if channel 1 has a higher priority than channel 3, and both request to switch to the same wavelength simultaneously, the synchronous drive circuit 703 immediately executes the switching command for the filter corresponding to channel 1, while inserting a 5ms delay for the filter corresponding to channel 3, and automatically assigning it the nearest unoccupied wavelength in the mapping table. This conflict avoidance mechanism effectively prevents instantaneous current overload and inter-channel interference, ensuring the synchronization and stability of the 16-channel signal scheduling.

[0037] During dynamic operation, the 16 power equalization sub-signals output by the beam splitter 600 are transmitted to the input of the wavelength selection component 700 via 16 independent optical fibers. The input is fixed with precision clamps to ensure a one-to-one correspondence between the 16 sub-signals and the entrance ports of the 16 MEMS tunable filters 702, and that the optical signals are incident perpendicularly into the Fabry-Perot cavity of each tunable filter 702 to guarantee the accuracy of the resonance condition. The synchronous drive circuit 703 applies a precise drive voltage to the corresponding MEMS tunable filter 702. The electrostatic drive unit (comb structure) of each MEMS tunable filter 702 generates electrostatic force under voltage, pulling the two micromirrors to the target spacing. An integrated capacitive position sensor collects spacing data in real time, ensuring the spacing accuracy matches the target wavelength. Once the micromirror spacing is precisely locked, the Fabry-Perot cavity only allows the optical signal of the target wavelength to meet the resonance condition and be transmitted; other wavelengths are reflected and absorbed by the light-absorbing coating on the surface of the ceramic substrate 701, thus avoiding wavelength crosstalk. Finally, the 16 target wavelength signals selected by the 16 MEMS tunable filters 702 are transmitted to the subsequent optical combining output component 800 through the output fiber array. The 16 fibers in this fiber array have been pre-grouped by channel (e.g., fibers 1-4 correspond to channel 1, fibers 5-8 correspond to channel 2, and so on), ensuring that the four wavelength signals in the same channel can enter the same optical combining unit of the optical combining output component 800.

[0038] A further preferred embodiment of the light combining output component 800 is as follows: Figure 2 , Figure 4 and Figure 7 As shown, the optical combining output component 800 (with a combining loss ≤0.4dB) includes a combining housing 805 and input interfaces 801 (distributed in 4 groups × 4 on the input end panel of the combining housing 805, each group corresponding to one arrayed waveguide grating combiner 806, with a precision V-groove on the inner side (adapted to the outer diameter of the output fiber of the wavelength selection component 700). Fiber optic connectors are fixed with UV adhesive to ensure minimal optical path alignment deviation. The 16 interfaces respectively receive 16 sub-signals (4 channels, 4 wavelengths per channel) output from the wavelength selection component 700, and guide the 4 sub-signals of the same channel to the corresponding arrayed waveguide grating combiner 806. The 4 input waveguides are arranged in parallel, each connecting to one group of 4 interfaces of the input interface 801 to receive the 4 target wavelength sub-signals of the same channel. The arrayed waveguide region converges the 4 target wavelengths into one output channel. The output waveguide is single-channel, transmitting the synthesized multi-wavelength signals to the power flattening circuit 804, the beam combining processing unit, the cooperative output connection component 802, and the single output connection component 803. The beam combining processing unit synthesizes the wavelength-selected sub-signals into multiple output signals according to wavelength, and outputs them externally through the cooperative output connection component 802 and the single output connection component 803 as needed. The beam combining output component 800 includes four arrayed waveguide grating beam combiners 806, which are disposed within the beam combining housing 805. The channels of each arrayed waveguide grating beam combiner 806 are spaced apart. The output end of the arrayed waveguide grating beam combiner 806 is equipped with a power flattening circuit 804, which is used to stabilize the output power fluctuation. The output end of the power flattening circuit 804 is connected to the cooperative output connection component 802 and the single output connection component 803.

[0039] First, the 16 sub-signals (4 channels, 4 target wavelengths per channel) output by the wavelength selection component 700 are connected to the input interface 801 via 16 optical fibers. The V-groove inside the input interface 801 ensures precise alignment of the fiber optic connectors. The input interface 801, according to channel grouping logic, guides the 4 sub-signals of the same channel to the 4 input waveguides of the corresponding array waveguide grating combiner 806. For example, the 1st to 4th interfaces of the input interface 801 correspond to channel 1, and the 4 sub-signals are transmitted to the first array waveguide grating combiner 806; the 5th to 8th interfaces correspond to channel 2, and the signals are transmitted to the second array waveguide grating combiner 806, and so on.

[0040] Four target wavelength sub-signals from the same channel enter the input waveguide of the corresponding arrayed waveguide grating combiner 806, allowing the sub-signals to enter the arrayed waveguide region. The four sub-signals then enter the four input waveguides of the arrayed waveguide grating combiner 806, subsequently propagating into the arrayed waveguide region. This results in different optical path differences between the multiple tapered waveguides in this region, causing the four wavelength sub-signals to propagate through different waveguides. Due to these optical path differences, the four target wavelength sub-signals arrive simultaneously at the output waveguide port of the arrayed waveguide grating combiner 806. During the process of converging into a single composite signal containing four wavelengths through the superposition effect of light, stray light of non-target wavelengths (such as signals not fully filtered by the wavelength selection component 700) will not converge at the output end due to the mismatch in optical path differences and will be absorbed by the inner wall of the arrayed waveguide grating combiner 806, thus achieving selective beam combining. The arrayed waveguide grating combiner 806 receives one group (four signals) of light. The wavelength signals output by the MEMS tunable filter (such as the 1530nm, 1535nm, 1540nm, and 1545nm signals selected by the first arrayed waveguide grating combiner 806) are combined into one output signal containing four target wavelengths, and finally transmitted to the 5G core network switching equipment through four sets of output PMFs.

[0041] The converged single-channel multi-wavelength signal is then transmitted to the subsequent power flattening circuit 804 through the output waveguide of the arrayed waveguide grating combiner 806. The power flattening circuit 804 is located at the output end of each arrayed waveguide grating combiner 806 and includes a high splitting ratio monitoring splitter, a photodetector array calibrated for standard wavelengths, and a dedicated fast gain equalization chip. This allows a small amount (about 1%) of the output light to be extracted as a monitoring signal by a splitter integrated in the optical path. Subsequently, the monitoring signal enters a wavelength demultiplexer based on the arrayed waveguide grating and is separated to the corresponding germanium-silicon photodetector, where it is converted into independent electrical signals for each wavelength. These converted electrical signals are compared with the preset target voltage value in the transimpedance amplifier and comparator circuit. The resulting error signal is applied to the thin-film heater array based on the thermo-optic effect through an analog drive circuit. This causes the thin-film heater array to precisely change the temperature of the waveguide attenuation region corresponding to each wavelength channel, thereby achieving independent and continuous fine-tuning of the optical power of each wavelength. Ultimately, this ensures that the four output wavelengths are controlled to have consistent power flatness.

[0042] Four arrayed waveguide grating combiners 806 synchronously perform the above actions, combining 16 sub-signals into four multi-wavelength output signals (each containing four target wavelengths). The combined multi-wavelength signals then enter a power flattening circuit 804, where the optical power detector collects the power of each of the four wavelengths in the combined signal in real time and converts the power into a weak current signal. This current signal is then converted into a digital signal by an AD converter and transmitted to a microprocessor. The microprocessor analyzes and judges the signal, and based on the deviation, sends adjustment commands to four variable optical attenuators. For wavelengths with positive deviations, the microprocessor increases the adjustment value. The attenuation of the variable optical attenuator is reduced for wavelengths with negative deviations, resulting in a low response time of the variable optical attenuator during adjustment, ensuring rapid power stabilization. During this process, the optical power detector collects the adjusted power data again and feeds it back to the microprocessor. If the power fluctuation of all wavelengths does not exceed the threshold, the power flattening is considered complete. If it still exceeds the threshold, the detection and adjustment are repeated until the target is met, so that the four power flattening circuits 804 work synchronously, ensuring that the power of the four synthesized signals is stable within the target range, avoiding overload or weak signal of external optical equipment (such as optical amplifiers) due to uneven power.

[0043] The microprocessor sends output mode commands to the optical combining output component 800 via control interface 807. The optical combining output component 800 selects the output path according to the command. If the command is for coordinated output, the four power-flattened combined signals directly enter the four interfaces of the coordinated output connection component 802. Each interface's built-in fiber optic isolator blocks external reflected light backflow, ensuring unidirectional signal transmission. The four signals are simultaneously output to four devices in the external optical network (such as four switches), enabling multi-channel parallel scheduling and adapting to scenarios with simultaneous transmission of multiple services. If the command is for single output (e.g., a core service channel requiring separate backup), the microprocessor designates a specific combined signal (e.g., channel 1), and the 1×4 optical switch operates, guiding this signal to the single output connection component 803. This interface also ensures signal purity through fiber optic isolators, transmitting the core service signal to the backup device to ensure uninterrupted core services. These two output modes can be switched in real-time via control interface 807 without downtime, improving equipment flexibility.

[0044] The output panel of the optical combining output component 800 has a built-in optical power monitoring port (LC / APC interface). It extracts the corresponding optical power from the four combined signals through a 1×4 optical beam splitter, connects to the built-in optical power meter for detection, and triggers the wavelength selection component 700 to re-execute the wavelength selection process to try to recover the signal. If the power is detected to be stable for a long time, it is determined that the optical combining output component 800 is working normally and continuously outputs the signal.

[0045] Based on the above, this embodiment was tested in a laboratory environment (temperature 25°C, input optical power 0dBm), and the results are as follows: Insertion loss: 2.2-2.8dB (average 2.5dB); Polarization-dependent loss (PDL): 0.3-0.45 dB (average 0.4 dB); Wavelength switching speed: 8-9.5ms (average 9ms); Polarization crosstalk: -42~-45dB; Operational stability: After 72 hours of continuous operation, the output power fluctuation is ≤ ±0.1dB, with no wavelength drift.

[0046] The overall selection switch has an insertion loss of ≤3dB, a polarization dependent loss (PDL) of ≤0.5dB, and a polarization crosstalk of ≤-40dB. Based on this, it can be directly applied to scenarios such as 5G core networks, data center interconnection, and long-distance trunk transmission. It supports flexible scheduling of 100G / 200G / 400G signals, helping optical communication networks upgrade to high capacity and high flexibility.

[0047] Further preferred, based on Figure 1 and Figure 2 As shown, a heat dissipation control terminal 300 (which can adopt existing heat dissipation methods) is installed on the side of the housing 100, and multiple sets of control communication terminals 400 (evenly distributed on the bottom panel of the housing 100) are installed on the bottom of the housing 100. An output polarization-maintaining fiber optic interface 200 is installed on the left side of the housing 100. This is existing technology and will not be described in detail.

[0048] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polarization-insensitive four-channel four-wavelength selective switch, characterized in that, include: The housing (100) and the input component, polarization processing component (500), beam splitting component (600), wavelength selection component (700) and beam combining output component (800) installed inside it in sequence via optical paths. The input component is used to receive multiple input optical signals; The polarization processing component (500) includes an integrated quartz substrate (501), multiple polarization processing units (502), and a microlens array (507). The multiple polarization processing units (502) are integrated on the surface of the integrated quartz substrate (501) and are used to unify the polarization state of each input optical signal to a predetermined polarization state. The microlens array (507) is optically coupled to the beam splitter (600). The wavelength selection component (700) includes an integrated substrate and a plurality of tunable filters (702) disposed thereon for independently selecting wavelengths for multiple sub-signals; The light combining output component (800) includes a light combining shell (805), an input interface (801), a light combining processing unit, a cooperative output connection component (802), and a single output connection component (803). The light combining processing unit combines wavelength-selected sub-signals into multiple output signals according to wavelength, and outputs them to the outside through the cooperative output connection component (802) and the single output connection component (803) respectively as needed.

2. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The polarization processing unit (502) outputs two sets of optical paths (505) at its side ends. The two sets of optical paths (505) are connected to a half-wave plate (506) at their side ends. The half-wave plate (506) is connected to an output channel (504) at its side end. A coupling loss protection layer is laid on the outside of the output channel (504).

3. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The input component includes four sets of polarization-maintaining optical fibers arranged in parallel, and the output ends of the polarization-maintaining optical fibers are respectively adapted and connected to the output channel (504).

4. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The polarization processing component (500) is an integrated polarization processing chip. The integrated quartz substrate (501) integrates four sets of polarization beam splitters (508) and four half-wave plates (506). The spacing between adjacent polarization beam splitters (508) is the same as the spacing between multiple polarization processing units (502). The half-wave plates (506) are set at a 45° angle to the reflected light path of the polarization beam splitters (508).

5. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The microlens array (507) is disposed at the output end of the integrated polarization processing chip. The array microlenses of the microlens array (507) correspond to the output optical path of the polarization processing unit (502) and are used to couple the optical signal to the optical coupler (601).

6. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The beam splitting assembly (600) includes four optical couplers (601), a beam splitting processing unit (602), and a channel power equalizer (604). Each optical coupler (601) corresponds to one beam splitting path (605) on the side of the beam splitting processing unit (602). The connection end of the beam splitting processing unit (602) and the channel power equalizer (604) is connected to a 4×4-channel output terminal (603). The beam splitting processing unit (602) splits each polarized optical signal into multiple sub-signals.

7. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: Multiple tunable filters (702) are MEMS tunable filters and are integrated in a matrix on the same ceramic substrate (701). A receiver (704) is connected to the side of the ceramic substrate (701). The receiver (704) is connected to the output optical path of the input optical path (601). A synchronous driving circuit (703) is installed inside the ceramic substrate (701). The synchronous driving circuit (703) is used to control the MEMS tunable filters (702). The synchronous driving circuit (703) is a control circuit. The control circuit configures the wavelength selection rules in real time through a preset wavelength channel mapping table.

8. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The beam combining output component (800) includes four arrayed waveguide grating beam combiners (806), which are disposed inside the beam combining housing (805). The channels of each arrayed waveguide grating beam combiner (806) are spaced apart. The output end of each arrayed waveguide grating beam combiner (806) is provided with a power flattening circuit (804). The power flattening circuit (804) is used to stabilize the output power fluctuation. The output end of the power flattening circuit (804) is connected to a cooperative output connection component (802) and a single output connection component (803).

9. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The housing (100) is provided with a heat dissipation control terminal (300) on its side and multiple control communication terminals (400) are provided at the bottom of the housing (100).

10. The polarization-insensitive four-channel four-wavelength selective switch according to claim 1, characterized in that: The left end of the housing (100) is provided with an output polarization-maintaining fiber optic interface (200).

Images