A double-y silicon optical waveguide mode filter performance test system and method

Abstract

This invention discloses a dual-Y silicon optical waveguide mode filtering performance testing system and method, relating to the field of silicon-based optoelectronic device testing technology. The system comprises: a tunable laser source module, an optical path distribution and polarization control module, a device-under-test (DUT) interface and coupling module, an optical signal receiving and detection module, and a system control and data processing module. Rapid switching between TEO and TMO modes is achieved through polarization beam splitting and optical switching gating. Parallel measurement of insertion loss and port reflectivity is achieved through the synchronous arrangement of three optical power meters. Transmission extinction ratio and reflection extinction ratio are calculated, and bidirectional consistency verification is achieved through an optical path reversal switching unit. This system comprehensively and efficiently characterizes the mode filtering performance of coated dual-Y silicon optical waveguide devices across the entire operating wavelength range, providing reliable testing support for film system design optimization, fabrication process feedback, and silicon optical gyroscope system integration.

Description

Technical Field

[0001] This invention relates to the field of silicon-based optoelectronic device testing technology, specifically to a dual-Y silicon optical waveguide mode filtering performance testing system and method. Background Technology

[0002] Silicon-based optoelectronics technology has become a research hotspot in the field of inertial navigation due to its compatibility with CMOS processes and high integration. In silicon photonic gyroscopes based on the Sagnac effect, the Y-branch waveguide serves as the core optical splitter and combiner, and its performance directly affects the system sensitivity and zero-bias stability of the gyroscope. To further improve the accuracy of the gyroscope, existing technologies deposit multilayer dielectric films on the surface of the Y-branch waveguide, utilizing the difference in reflectivity between the TEO fundamental mode and higher-order modes to achieve mode filtering and suppress noise introduced by higher-order modes. However, the actual filtering effect of this coating structure is affected by multiple process factors such as film thickness error, refractive index deviation, interface roughness, and residual stress. The theoretical design value is often difficult to fully reproduce after fabrication. Therefore, accurately characterizing the actual mode filtering performance of the device has become a key aspect in engineering applications.

[0003] For dual-Y silicon optical waveguide devices with multilayer dielectric films deposited on the surface, the films are used to achieve mode filtering by utilizing the reflectivity difference between the TEO fundamental mode and the TM0 higher-order mode. Traditional optical testing methods are mostly designed for single polarization states or discrete waveguide elements, which cannot simulate the actual state of beam splitting and combining in the dual-Y working optical path. It is even more difficult to simultaneously obtain the complete response of the fundamental mode and higher-order modes in both transmission and reflection dimensions. The polarization control capability of the testing system is insufficient, making it difficult to stably generate high-purity TEO or TM0 mode excitation light over a wide spectral range, resulting in mode crosstalk affecting measurement accuracy. At the same time, the lack of a synchronous monitoring mechanism for the reflection signal at the input port in the testing process leads to the absence of the key evaluation index of reflection extinction ratio, making it impossible to fully evaluate the ability of the film system to suppress backward propagating spurious modes.

[0004] The prior art CN104280215A discloses a bidirectional multi-axis angle automatic testing device for the dual-channel optical performance of a Y-waveguide. This device realizes forward and reverse testing of the dual channels of the Y-waveguide through an optical signal axis-switching mechanism and an optical signal channel direction switching mechanism. However, it only tests the polarization crosstalk and optical path parameters of the uncoated Y-waveguide and does not involve the testing of the mode filtering performance (transmission extinction ratio and reflection extinction ratio) unique to coated devices, nor does it consider the evaluation of the film system's ability to suppress reverse propagation spurious modes.

[0005] In summary, to meet the stringent quality control requirements of high-performance silicon optical gyroscopes for coated dual Y waveguide devices, it is urgent to develop a dedicated testing system and method that can simulate the actual working state of the device, specifically for the film mode filtering characteristics of coated devices, and cover the transmission and reflection performance of the fundamental mode / higher-order modes. This will provide comprehensive and accurate test feedback for the iterative optimization of film system design and fabrication processes. Summary of the Invention

[0006] To address the shortcomings of existing technologies, such as the lack of a dedicated testing scheme for the mode filtering performance of coated double-Y silicon optical waveguides, the inability to simultaneously acquire the complete responses of the fundamental and higher-order modes in the transmission and reflection dimensions, and measurement deviations caused by insufficient polarization control accuracy, this invention designs a dual-Y silicon optical waveguide mode filtering performance testing system and method. The system comprises: a tunable laser source module, an optical path distribution and polarization control module, a device-under-test (DUT) interface and coupling module, an optical signal receiving and detection module, and a system control and data processing module. Rapid switching between TE0 and TM0 modes is achieved through polarization beam splitting and optical switching gating. Parallel measurement of insertion loss and port reflectivity is achieved through the synchronous arrangement of three optical power meters. Transmission extinction ratio and reflection extinction ratio are calculated, and bidirectional consistency verification is achieved through an optical path reversal switching unit. This system comprehensively and efficiently characterizes the mode filtering performance of coated double-Y silicon optical waveguide devices across the entire operating wavelength range, providing reliable testing support for film system design optimization, fabrication process feedback, and silicon optical gyroscope system integration.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On one hand, a dual-Y silicon optical waveguide mode filtering performance testing system, comprising: a tunable laser source module, an optical path distribution and polarization control module, a device under test (DUT) interface and coupling module, an optical signal receiving and detection module, and a system control and data processing module; wherein, the dual-Y silicon optical waveguide DUT is a coated dual-Y silicon optical waveguide with a multilayer dielectric film system deposited on its surface, the multilayer dielectric film system being used to achieve mode filtering by utilizing the reflectivity difference between the TEO fundamental mode and the TMO higher-order modes; The tunable laser source module is used to output narrow-linewidth test light with adjustable wavelength and stable power. The optical path allocation and polarization control module is set on the output optical path of the tunable laser source module. The optical path allocation and polarization control module is used to convert the test light into high-purity TEO fundamental mode test light or TEO higher-order mode test light, and allocate the test light to the input port of the dual Y silicon optical waveguide device under test. The device under test (DUT) interface and coupling module is located between the optical path distribution and polarization control module and the dual Y silicon waveguide device under test. The DUT interface and coupling module is used to couple the test light into the input Y branch of the dual Y silicon waveguide device under test and collect the optical signals reflected back from the output Y branch and the input port of the dual Y silicon waveguide device under test. The optical signal receiving and detection module is located at the output end of the interface and coupling module of the device under test. The optical signal receiving and detection module is used to measure the input optical power of the test light, the transmitted optical power after passing through the dual Y silicon waveguide device under test, and the reflected optical power reflected back from the input port. The system control and data processing module is connected to the tunable laser source module, the optical path allocation and polarization control module, and the optical signal receiving and detection module, respectively. The system control and data processing module is used to control wavelength scanning and polarization state switching, and to collect and process optical power data to calculate mode filtering performance parameters.

[0008] Furthermore, the optical path allocation and polarization control module includes a polarization controller, a polarization beam splitter, and an optical switch, which are sequentially connected to the output optical path of the tunable laser source module. The polarization controller is used to adjust the polarization state of the test light; The polarization beam splitter is used to split the adjusted test light into a TE0 polarization branch and a TM0 polarization branch. The TE0 polarization branch corresponds to linearly polarized light with a polarization direction parallel to the waveguide plane of the device under test, and the TM0 polarization branch corresponds to linearly polarized light with a polarization direction perpendicular to the waveguide plane of the device under test. The polarization extinction ratio of the two polarized lights output by the polarization beam splitter is greater than 25dB. The optical switch is used to selectively conduct the TEO polarization branch light or the TMEO polarization branch light to output the high-purity TEO fundamental mode test light or the TMEO higher-order mode test light accordingly.

[0009] Furthermore, the interface and coupling module of the device under test includes a six-dimensional adjustment frame and an input lens fiber and an output lens fiber fixed on the six-dimensional adjustment frame; The input lens fiber is used to couple the test light into the input Y branch of the dual Y silicon waveguide device under test with low loss; The output lens fiber is used to stably collect the transmitted light power output from the output Y branch of the dual Y silicon waveguide device under test and the reflected light power reflected back from the input port.

[0010] Furthermore, the optical signal receiving and detection module includes a first optical power meter, a second optical power meter, and a third optical power meter; The first optical power meter is disposed at the output end of the optical path distribution and polarization control module and is used to measure the input optical power of the test light input to the dual Y silicon waveguide device under test; The second optical power meter is disposed at the output end of the output lens fiber and is used to measure the transmitted light power after passing through the dual Y silicon waveguide device under test; The third optical power meter is installed at the reflected light collection end of the input lens fiber and is used to measure the power of the reflected light reflected back from the input port.

[0011] Furthermore, the system control and data processing module calculates the fundamental mode insertion loss and the fundamental mode input port reflectivity based on the power values ​​measured by the first optical power meter, the second optical power meter, and the third optical power meter, wherein the fundamental mode insertion loss... The reflectivity of the fundamental mode input port ,in, The input optical power measured by the first optical power meter. The second optical power meter measures the TE0 mode transmitted light power when the optical switch is turned on in the TE0 polarization branch. The third optical power meter measures the reflected optical power of the TE0 mode when the optical switch is turned on in the TE0 polarization branch.

[0012] Furthermore, the system control and data processing module also calculates the higher-order mode insertion loss and the higher-order mode input port reflectivity based on the power values ​​measured by the first optical power meter, the second optical power meter, and the third optical power meter, wherein the higher-order mode insertion loss... The reflectivity of the higher-order mode input port ,in, The second optical power meter measures the transmitted optical power of the TM0 mode when the optical switch is conducting the TM0 polarization branch. The third optical power meter measures the reflected optical power of the TM0 mode when the optical switch is turned on in the TM0 polarization branch.

[0013] Furthermore, the system control and data processing module calculates the mode filtering extinction ratio based on the fundamental mode insertion loss, the fundamental mode input port reflectivity, the higher-order mode insertion loss, and the higher-order mode input port reflectivity. The mode filtering extinction ratio includes the transmission extinction ratio and the reflection extinction ratio. The transmission extinction ratio The reflection extinction ratio ; The transmission extinction ratio and the reflection extinction ratio are used to characterize the ability of the double Y silicon waveguide device under test to distinguish between the fundamental mode and higher-order modes.

[0014] Furthermore, the system control and data processing module controls the tunable laser source module to perform wavelength scanning in steps within a preset wavelength range, and simultaneously records the mode filtering performance parameters at each wavelength point to generate the performance response curve of the dual Y silicon optical waveguide device under test within the working wavelength range. The device under test interface and coupling module also includes an optical path reversal switching unit. The optical path reversal switching unit includes a 2×2 optical switch. The 2×2 optical switch is connected between the output end of the optical path distribution and polarization control module and the input lens fiber and the output lens fiber. It is used to guide the test light to the input lens fiber and guide the transmitted light collected by the output lens fiber to the second optical power meter in the forward test mode, and to guide the test light to the output lens fiber and guide the transmitted light collected by the input lens fiber to the second optical power meter in the reverse test mode.

[0015] On the other hand, a method for testing the mode filtering performance of a dual-Y silicon optical waveguide, the specific steps of which are as follows: S100: Start the tunable laser source module for preheating, and perform system background noise and insertion loss benchmark calibration through the system control and data processing module; S200, through the system control and data processing module, controls the optical path allocation and polarization adjustment module to output high-purity TEO fundamental mode test light, and reads the first optical power meter, the second optical power meter, and the third optical power meter respectively to obtain the corresponding input optical power. TE0 mode transmitted light power and TE0 mode reflected light power And calculate the fundamental mode insertion loss. and fundamental mode input port reflectivity ; S300, through the system control and data processing module, controls the optical path allocation and polarization adjustment module to switch the output of TM0 high-order mode test light, and reads the first optical power meter, the second optical power meter, and the third optical power meter respectively to obtain the corresponding input optical power. TM0 mode transmitted light power and TM0 mode reflected light power And calculate the insertion loss of higher-order modes. and higher-order mode input port reflectivity ; S400, the system control and data processing module obtains the fundamental mode insertion loss in step S200. and fundamental mode input port reflectivity And the higher-order mode insertion loss obtained in step S300 and higher-order mode input port reflectivity The transmission extinction ratio was calculated. and reflection extinction ratio ; S500: The system control and data processing module controls the tunable laser source module to perform wavelength scanning in steps within the operating wavelength range, and repeats steps S200 to S400 for each wavelength point to obtain the transmission extinction ratio corresponding to each wavelength point. and reflection extinction ratio To plot the mode filtering extinction ratio curve of the double Y silicon optical waveguide device under test in the operating wavelength range.

[0016] Compared with existing technologies, this dual-Y silicon optical waveguide mode filtering performance testing system and method has the following advantages: This invention, through a cascaded design of a polarization controller and a polarization beam splitter, combined with a fast gating mechanism of an optical switch, can stably output high-purity TE0 fundamental mode or TMO higher-order mode test light over a wide spectral range, eliminating the negative impact of mode crosstalk on measurement accuracy. Simultaneously, the system, through the synchronous arrangement of three independent optical power meters, achieves simultaneous acquisition and recording of input optical power, transmitted optical power, and input port reflected optical power. This simulates the real-world working scenario of the device in a Sagnac ring where beam splitting and combining coexist, providing a more realistic quantitative basis for the feasibility of the device's application in gyroscope systems.

[0017] This invention drives an optical switch to automatically switch between TEO and TMO modes according to preset logic via a system control and data processing unit, and simultaneously controls a tunable laser source to automatically scan in steps within its operating wavelength range. At each wavelength point, the insertion loss and reflectivity of the fundamental mode and higher-order modes are automatically calculated, thereby generating spectral response curves of transmission extinction ratio and reflection extinction ratio. This automated testing architecture significantly improves testing efficiency and data repeatability, eliminates random errors introduced by manual operation, and provides an intuitive and detailed data foundation for bandwidth verification and temperature sensitivity analysis of film system design. It can directly guide the fine-tuning compensation of film thickness, thereby shortening the device development cycle.

[0018] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0020] Figure 1 This is a data flow diagram of a dual-Y silicon optical waveguide mode filtering performance testing system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the interface and coupling module structure of the device under test in an embodiment of the present invention; Figure 3 This is a flowchart of a method for testing the mode filtering performance of a dual-Y silicon optical waveguide in an embodiment of the present invention. Detailed Implementation

[0021] To better understand the above technical solutions, a detailed description of the solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, the terms "first," "second," etc., are used only to distinguish different structures, components, or steps, and do not constitute any limitation on their order, importance, or function. In the embodiments of this invention, "connection" should be interpreted broadly; for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that allows communication; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] This invention provides a dual-Y silicon optical waveguide mode filtering performance testing system, which is particularly suitable for, but not limited to, performance evaluation of dual-Y branched silicon optical waveguide devices with multilayer dielectric films deposited on their surfaces. To better illustrate the specific implementation of this invention, a detailed description will be provided below using a specific test scenario. In this test scenario, the device under test is a dual-Y silicon optical waveguide fabricated on a silicon-on-insulator (SOI) material platform. Both its input and output ports are end-face coupler structures, and its operating wavelengths cover the S-band, C-band, and L-band commonly used in optical communication and silicon optical gyroscopes.

[0024] In this embodiment, as Figure 1As shown, a dual-Y silicon optical waveguide mode filtering performance testing system comprises: a tunable laser source module, an optical path allocation and polarization control module, a device-under-test (DUT) interface and coupling module, an optical signal receiving and detection module, and a system control and data processing module. Specifically: the output of the tunable laser source module is connected to the input of the optical path allocation and polarization control module via a polarization-maintaining fiber; the output of the optical path allocation and polarization control module is connected to the optical signal input of the DUT interface and coupling module via a polarization-maintaining fiber; the DUT interface and coupling module is connected to the input and output ports of the dual-Y silicon optical waveguide under test (DUT) via end-face coupling to achieve optical signal input and collection; the input of the optical signal receiving and detection module is connected to the transmitted light output port and reflected light output port of the DUT interface and coupling module; and the system control and data processing module is connected to the tunable laser source module, the optical path allocation and polarization control module, and the optical signal receiving and detection module via a GPIB bus or USB data cable to send control commands and acquire measurement data in real time.

[0025] In this embodiment, the tunable laser source module outputs a wide wavelength range from 1260nm to 1680nm. The laser has a built-in wavelength locking unit to ensure the accuracy and repeatability of the output wavelength. The output pigtail is a PANDA-type polarization-maintaining fiber, with its slow axis aligned with the output polarization direction of the laser's internal optical path to ensure the stable polarization state of the output light during transmission. During startup, the tunable laser source module receives instructions from the system control and data processing module to preheat, allowing the internal temperature of the laser to reach thermal equilibrium, thereby ensuring the long-term stability of the output light power and wavelength. After preheating, the system control and data processing module sends wavelength setting and power setting commands to the tunable laser source module via the GPIB interface, causing it to output continuous narrow-linewidth test light with the specified wavelength and power.

[0026] In this embodiment, the optical path allocation and polarization control module is used to convert the test light output from the tunable laser source module into high-purity TEO fundamental mode test light or TMO higher-order mode test light, and allocate it to the input port of the dual-Y silicon optical waveguide device under test. Specifically, the module includes a polarization controller, a polarization beam splitter, and an optical switch connected in sequence via polarization-maintaining fiber.

[0027] The polarization controller employs a three-ring mechanical polarization controller, with its three ring-shaped waveplates corresponding to a quarter-wave plate, a half-wave plate, and a quarter-wave plate, respectively. During the initial system calibration phase, the polarization state of the input light is adjusted by rotating the three ring-shaped waveplates in conjunction with the polarization beamsplitter and optical power meter, ensuring that the extinction ratios output from both orthogonal output ports of the polarization beamsplitter reach their maximum values. After adjustment, the state of the polarization controller is fixed to ensure that the polarization state of the input light remains unchanged throughout the entire test process. In this embodiment, after calibration, the polarization extinction ratios of both the TE0 and TM0 polarization branches output by the polarization beamsplitter are greater than 25 dB.

[0028] The polarization beamsplitter is a birefringent crystal-based polarization beamsplitter using YVO4 crystals, with an operating wavelength range of 1260 nm to 1680 nm. This beamsplitter splits the adjusted test light into two orthogonally polarized beams: a TE0 polarization branch and a TM0 polarization branch. The TE0 polarization branch corresponds to polarized light with its polarization direction parallel to the waveguide plane of the device under test (i.e., horizontal direction), while the TM0 polarization branch corresponds to polarized light with its polarization direction perpendicular to the waveguide plane of the device under test (i.e., vertical direction).

[0029] The optical switch employs a 1×2 magneto-optical switch. Its common port connects to the output of the polarization beamsplitter, and its two selectable ports output TE0 and TM0 polarization branches, respectively. The system control and data processing module controls the optical switch to selectively conduct either the TE0 or TM0 polarization branch by sending a TTL-level signal. When the TE0 polarization branch is activated, the optical switch outputs high-purity TE0 fundamental mode test light; when the TM0 polarization branch is activated, it outputs high-purity TM0 higher-order mode test light. The output of the optical switch is connected to the interface of the device under test (DUT) and the input of the coupling module via polarization-maintaining fiber. This polarization-maintaining fiber uses an FC / APC fiber optic connector to reduce the impact of end-face reflections on the test results.

[0030] like Figure 2 As shown, the device under test (DUT) interface and coupling module is located between the optical path distribution and polarization control module and the DUT double-Y silicon waveguide. It is used to couple the test light into the input Y branch of the DUT with low loss and to collect the optical signals reflected from the output Y branch and input port of the DUT. This module includes a six-dimensional adjustment frame and input and output lens fibers fixed on the frame. The adjustment resolution of the six-dimensional adjustment frame on the X, Y, and Z translation axes and the pitch, yaw, and roll rotation axes is better than 10 nm, ensuring the alignment accuracy between the fiber and the waveguide end face.

[0031] The input lens fiber is a lens-tipped fiber, and its mode field diameter matches the mode field diameter of the input port of the dual-Y silicon waveguide under test. This input lens fiber is fixed on a six-dimensional adjustment frame. By finely adjusting the six-dimensional adjustment frame, the test light output from the optical switch is coupled into the input Y branch of the dual-Y silicon waveguide under test with low loss via the input lens fiber using end-face coupling. This input lens fiber also functions as a reflected light collector, connected to a third optical power meter to collect the optical signal reflected back from the input port of the dual-Y silicon waveguide under test.

[0032] The output lens fiber also uses a lens-tipped fiber, with its mode field diameter matching that of the output port of the dual-Y silicon waveguide under test. It is fixed to another six-dimensional adjustment frame. By fine-tuning the six-dimensional adjustment frame, the transmitted light output from the Y-branch of the dual-Y silicon waveguide under test is stably collected by the output lens fiber. This output lens fiber is connected to a second optical power meter to transmit the collected transmitted light power to the second optical power meter for measurement.

[0033] In addition, the device under test (DUT) interface and coupling module also includes an optical path reversal switching unit. This unit comprises a 2×2 optical switch connected between the output of the optical switch and the input and output lens fibers. In forward test mode, the optical path reversal switching unit guides the test light output from the optical switch to the input lens fiber and guides the transmitted light collected by the output lens fiber to the second optical power meter. In reverse test mode, the optical path reversal switching unit guides the test light output from the optical switch to the output lens fiber, thereby reversing the input test light from the output Y branch of the dual-Y silicon waveguide under test and guiding the transmitted light collected by the input lens fiber to the second optical power meter. This design allows the same set of coupled optical paths to support bidirectional testing without the need for manual readjustment of fiber positions, ensuring consistency of bidirectional test conditions.

[0034] The optical signal receiving and detection module is used to measure the input optical power of the test light, the transmitted optical power after passing through the dual-Y silicon waveguide device under test, and the reflected optical power reflected back from the input port. This module includes a first optical power meter, a second optical power meter, and a third optical power meter. All three optical power meters employ InGaAs photodiode detectors, with a response wavelength range covering 800nm-1700nm, linearity better than ±0.5%, and an effective detection power range from -80dBm to +20dBm.

[0035] The first optical power meter is set at the output end of the optical path distribution and polarization control module via an optical fiber coupler, that is, on the optical path between the output end of the optical switch and the interface of the device under test and the coupling module. The 99:1 optical fiber coupler splits the output light of the optical switch, with 99% of the optical power entering the device under test and 1% entering the first optical power meter. The first optical power meter is used to monitor and record the actual input optical power of the test light input to the dual Y silicon waveguide device under test in real time, thereby eliminating the influence of light source power fluctuations and changes in optical path connection status on the measurement results.

[0036] The second optical power meter is installed at the output end of the output lens fiber and is used to measure the transmitted light power output from the output Y branch after passing through the dual Y silicon waveguide device under test. The transmitted light power includes the TE0 mode transmitted light power when the optical switch turns on the TE0 polarization branch and the TM0 mode transmitted light power when the optical switch turns on the TM0 polarization branch.

[0037] The third optical power meter is located at the reflected light collection end of the input lens fiber, i.e., the other port of the input lens fiber. The reflected light is separated by a fiber circulator or a 1:99 fiber beam splitter. When a fiber circulator is used, its input end is connected to the optical path reversal switching unit, its reflection end is connected to the input lens fiber, and its transmission end is connected to the third optical power meter. When a fiber beam splitter is used, it is connected in series between the input lens fiber and the optical path reversal switching unit, and its 1% reflected light branch is connected to the third optical power meter. This third optical power meter is used to measure the reflected light power from the input port of the dual-Y silicon waveguide device under test. This reflected light power includes the TE0 mode reflected light power when the optical switch is conducting the TE0 polarization branch, and the TM0 mode reflected light power when the optical switch is conducting the TM0 polarization branch.

[0038] The system control and data processing module employs an industrial control computer with an embedded data acquisition card. It connects via GPIB interfaces to the optical switches in the tunable laser source module and the optical path distribution and polarization control module, and via USB interfaces to the first, second, and third optical power meters. This module controls wavelength scanning and polarization state switching, and acquires and processes optical power data to calculate mode filtering performance parameters.

[0039] The system control and data processing module uses the input optical power measured by the first optical power meter. The second optical power meter measures the transmitted optical power of the TE0 mode when the optical switch is turned on in the TE0 resonant branch. and the TE0 mode reflected light power measured by the third optical power meter Calculate the fundamental mode insertion loss and fundamental mode input port reflectivity Fundamental mode insertion loss The calculation formula is: ,in, This represents the total insertion loss of the TE0 mode after passing through the device under test, encompassing the contributions of input coupling loss, waveguide transmission loss, Y-branch shunt loss, and output coupling loss. The fundamental mode input port reflectivity... The calculation formula is: ,in, This reflects the reflection characteristics of the film system at the device input port for the TEO mode. Furthermore, the system control and data processing module also considers the input optical power measured by the first optical power meter. The second optical power meter measures the transmitted optical power of the TM0 mode when the optical switch is conducting the TM0 polarization branch. and the reflected optical power of the TM0 mode measured by the third optical power meter. Calculate the insertion loss of higher-order modes and higher-order mode input port reflectivity Higher-order mode insertion loss The calculation formula is: High-order mode input port reflectivity The calculation formula is: The system control and data processing module is based on the fundamental mode insertion loss. , fundamental mode input port reflectivity Higher-order mode insertion loss and higher-order mode input port reflectivity The mode-filtered extinction ratio is calculated, which includes the transmission extinction ratio and the reflection extinction ratio. The transmission extinction ratio and reflection extinction ratio are key indicators characterizing the ability of the double-Y silicon optical waveguide device under test to distinguish between the fundamental mode and higher-order modes. Transmission extinction ratio... The calculation formula is: , A higher value indicates stronger suppression of higher-order modes in the transmission direction, meaning that the TE0 mode preferentially passes through while the TM0 mode is significantly attenuated. For coated double-Y waveguides, this index directly reflects the loss selectivity of the film system for higher-order modes, and the reflection extinction ratio. The calculation formula is: .

[0040] The system control and data processing module controls the tunable laser source module to perform wavelength scanning in steps within a preset wavelength range, and simultaneously records the mode filtering performance parameters at each wavelength point to generate the performance response curve of the dual-Y silicon optical waveguide device under test within the operating wavelength range. In this embodiment, the wavelength scanning range is 1520nm to 1580nm, the scanning step is 0.1nm, and a total of 601 wavelength sampling points are used. At each wavelength point, the system needs to complete the power measurement and parameter calculation of both TE0 and TM0 modes. A single full-band scan involves 1202 mode switching and power reading operations. At a wavelength point, after the optical switch switches to the TE0 branch, it waits 100ms to allow the optical switch state to stabilize before simultaneously reading the values ​​of the three optical power meters. After completing the TE0 mode measurement, the optical switch switches to the TM0 branch, and again waits 100ms before reading the values ​​of the three optical power meters.

[0041] During the data processing phase, the system control and data processing module can also process data at each wavelength point. and The curve is smoothed to eliminate the interference of random noise on its trend. Simultaneously, it can calculate the curve over the entire wavelength range. and The mean, standard deviation, and peak wavelength are used as comprehensive evaluation indicators of device quality. In this embodiment, after completing the forward test, the system also reverses the input of the test light from the output Y branch of the dual-Y silicon waveguide device under test through the optical path reversal switching unit, and makes the optical signal receiving and detection module measure the transmitted light power and reflected light power in the reverse input state accordingly, so as to realize the consistency verification of the bidirectional mode filtering performance of the dual-Y silicon waveguide device under test in the beam splitting and beam combining directions. The bidirectional test process is the same as the forward test, and the power measurement and parameter calculation of TE0 and TM0 modes are completed sequentially in the reverse input state to obtain the reverse transmission extinction ratio. and reverse reflection extinction ratio Then, compare the results with the forward test results to calculate the difference in bidirectional transmission extinction ratio. Difference between bidirectional reflection extinction ratio When the differences are all less than a preset threshold, it is determined that the mode filtering performance of the dual Y silicon waveguide device under test is consistent in the beam splitting direction and the beam combining direction; the performance symmetry of the device in the two transmission directions in the Sagnac ring can be quantitatively evaluated.

[0042] like Figure 3 As shown, this invention also provides a method for testing the mode filtering performance of dual-Y silicon optical waveguides. The specific steps of this method are as follows: S100: Start the tunable laser source module for preheating, and perform system background noise and insertion loss benchmark calibration through the system control and data processing module; S200, through the system control and data processing module, controls the optical path allocation and polarization adjustment module to output high-purity TEO fundamental mode test light, and reads the first optical power meter, the second optical power meter, and the third optical power meter respectively to obtain the corresponding input optical power. TE0 mode transmitted light power and TE0 mode reflected light power And calculate the fundamental mode insertion loss. and fundamental mode input port reflectivity ; S300, through the system control and data processing module, controls the optical path allocation and polarization adjustment module to switch the output of TM0 high-order mode test light, and reads the first optical power meter, the second optical power meter, and the third optical power meter respectively to obtain the corresponding input optical power. TM0 mode transmitted light power and TM0 mode reflected light power And calculate the insertion loss of higher-order modes. and higher-order mode input port reflectivity ; S400, the system control and data processing module obtains the fundamental mode insertion loss in step S200. and fundamental mode input port reflectivity And the higher-order mode insertion loss obtained in step S300 and higher-order mode input port reflectivity The transmission extinction ratio was calculated. and reflection extinction ratio ; S500: The system control and data processing module controls the tunable laser source module to perform wavelength scanning in steps within the operating wavelength range, and repeats steps S200 to S400 for each wavelength point to obtain the transmission extinction ratio corresponding to each wavelength point. and reflection extinction ratio To plot the mode filtering extinction ratio curve of the double Y silicon optical waveguide device under test in the operating wavelength range.

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A dual-Y silicon optical waveguide mode filtering performance testing system, characterized in that, The system comprises: a tunable laser source module, an optical path distribution and polarization control module, a device under test (DUT) interface and coupling module, an optical signal receiving and detection module, and a system control and data processing module; wherein, the DUT is a coated type double-Y silicon optical waveguide device with a multilayer dielectric film system deposited on its surface, wherein the multilayer dielectric film system is used to achieve mode filtering by utilizing the reflectivity difference between the TEO fundamental mode and the TMO higher-order modes; The tunable laser source module is used to output narrow-linewidth test light with adjustable wavelength and stable power. The optical path allocation and polarization control module is used to convert the test light into high-purity TEO fundamental mode test light or TMO higher-order mode test light, and allocate the test light to the input port of the dual Y silicon optical waveguide device under test; The device under test interface and coupling module is used to couple the test light into the input Y branch of the dual Y silicon waveguide device under test, and to collect the optical signals reflected back from the output Y branch and the input port of the dual Y silicon waveguide device under test. The optical signal receiving and detection module is used to simultaneously measure the input optical power of the test light, the transmitted optical power after passing through the dual Y silicon waveguide device under test, and the reflected optical power reflected back from the input port. The reflected optical power is used to calculate the reflection extinction ratio to characterize the ability of the multilayer dielectric film system to suppress reverse propagation spurious modes. The system control and data processing module is used to control wavelength scanning and polarization state switching, and to collect and process optical power data to calculate mode filtering performance parameters.

2. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 1, characterized in that, The optical path distribution and polarization control module includes a polarization controller, a polarization beam splitter, and an optical switch, which are sequentially connected to the output optical path of the tunable laser source module. The polarization controller is used to adjust the polarization state of the test light; The polarization beam splitter is used to split the adjusted test light into a TE0 polarization branch and a TM0 polarization branch. The TE0 polarization branch corresponds to linearly polarized light with a polarization direction parallel to the waveguide plane of the device under test, and the TM0 polarization branch corresponds to linearly polarized light with a polarization direction perpendicular to the waveguide plane of the device under test. The polarization extinction ratio of the two polarized lights output by the polarization beam splitter is greater than 25dB. The optical switch is used to selectively conduct the TEO polarization branch light or the TMEO polarization branch light to output the high-purity TEO fundamental mode test light or the TMEO higher-order mode test light accordingly.

3. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 1, characterized in that, The interface and coupling module of the device under test includes a six-dimensional adjustment frame and an input lens fiber and an output lens fiber fixed on the six-dimensional adjustment frame; The input lens fiber is used to couple the test light into the input Y branch of the dual Y silicon waveguide device under test; The output lens fiber is used to collect the transmitted light power output from the output Y branch of the dual Y silicon waveguide device under test and the reflected light power reflected back from the input port.

4. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 1, characterized in that, The optical signal receiving and detection module includes a first optical power meter, a second optical power meter, and a third optical power meter; The first optical power meter is disposed at the output end of the optical path distribution and polarization control module and is used to measure the input optical power of the test light input to the dual Y silicon waveguide device under test; The second optical power meter is disposed at the output end of the output lens fiber and is used to measure the transmitted light power after passing through the dual Y silicon waveguide device under test; The third optical power meter is installed at the reflected light collection end of the input lens fiber and is used to measure the power of the reflected light reflected back from the input port.

5. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 1, characterized in that, The system control and data processing module calculates the fundamental mode insertion loss and the fundamental mode input port reflectivity based on the power values ​​measured by the first, second, and third optical power meters. The fundamental mode insertion loss... The reflectivity of the fundamental mode input port ,in, The input optical power measured by the first optical power meter. The second optical power meter measures the TE0 mode transmitted light power when the optical switch is turned on in the TE0 polarization branch. The third optical power meter measures the reflected optical power of the TE0 mode when the optical switch is turned on in the TE0 polarization branch.

6. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 5, characterized in that, The system control and data processing module further calculates the higher-order mode insertion loss and the higher-order mode input port reflectivity based on the power values ​​measured by the first optical power meter, the second optical power meter, and the third optical power meter. The higher-order mode insertion loss... The reflectivity of the higher-order mode input port ,in, The second optical power meter measures the transmitted optical power of the TM0 mode when the optical switch is conducting the TM0 polarization branch. The third optical power meter measures the reflected optical power of the TM0 mode when the optical switch is turned on in the TM0 polarization branch.

7. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 6, characterized in that, The system control and data processing module calculates the mode filtering extinction ratio based on the fundamental mode insertion loss, the fundamental mode input port reflectivity, the higher-order mode insertion loss, and the higher-order mode input port reflectivity. The mode filtering extinction ratio includes the transmission extinction ratio and the reflection extinction ratio. The transmission extinction ratio The reflection extinction ratio ; The transmission extinction ratio and the reflection extinction ratio are used to characterize the ability of the double Y silicon waveguide device under test to distinguish between the fundamental mode and higher-order modes.

8. The dual-Y silicon optical waveguide mode filtering performance testing system according to claim 1, characterized in that, The system control and data processing module controls the tunable laser source module to perform wavelength scanning in steps within a preset wavelength range, and simultaneously records the mode filtering performance parameters at each wavelength point to generate the performance response curve of the dual Y silicon optical waveguide device under test within the working wavelength range. The device under test interface and coupling module also includes an optical path reversal switching unit. The optical path reversal switching unit includes a 2×2 optical switch. The 2×2 optical switch is connected between the output end of the optical path distribution and polarization control module and the input lens fiber and the output lens fiber. It is used to guide the test light to the input lens fiber and guide the transmitted light collected by the output lens fiber to the second optical power meter in the forward test mode, and to guide the test light to the output lens fiber and guide the transmitted light collected by the input lens fiber to the second optical power meter in the reverse test mode.

9. A method for testing the mode filtering performance of a dual-Y silicon optical waveguide, applicable to the dual-Y silicon optical waveguide mode filtering performance testing system described in any one of claims 1-8, characterized in that, The specific steps of this method are as follows: S100: Start the tunable laser source module for preheating, and perform system background noise and insertion loss benchmark calibration through the system control and data processing module; S200, through the system control and data processing module, controls the optical path allocation and polarization adjustment module to output high-purity TEO fundamental mode test light, and reads the first optical power meter, the second optical power meter, and the third optical power meter respectively to obtain the corresponding input optical power. TE0 mode transmitted light power and TE0 mode reflected light power And calculate the fundamental mode insertion loss. and fundamental mode input port reflectivity ; S300, through the system control and data processing module, controls the optical path allocation and polarization adjustment module to switch the output of TM0 high-order mode test light, and reads the first optical power meter, the second optical power meter, and the third optical power meter respectively to obtain the corresponding input optical power. TM0 mode transmitted light power and TM0 mode reflected light power And calculate the insertion loss of higher-order modes. and higher-order mode input port reflectivity ; S400, the system control and data processing module obtains the fundamental mode insertion loss in step S200. and fundamental mode input port reflectivity And the higher-order mode insertion loss obtained in step S300 and higher-order mode input port reflectivity The transmission extinction ratio was calculated. and reflection extinction ratio ; S500: The system control and data processing module controls the tunable laser source module to perform wavelength scanning in steps within the operating wavelength range, and repeats steps S200 to S400 for each wavelength point to obtain the transmission extinction ratio corresponding to each wavelength point. and reflection extinction ratio To plot the mode filtering extinction ratio curve of the double Y silicon optical waveguide device under test in the operating wavelength range.

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