A device and method for testing characteristic parameters of silicon photonic chips for silicon photonic gyroscopes

Abstract

The present invention provides a device and method for testing characteristic parameters of silicon photonic chips for silicon photonic gyroscopes. The device adopts an electrically controlled optical switch to control the gating of the output pigtail optical path of the silicon photonic chip to be tested, and adopts an analog switch to control the gating of the test items; adopts a test and control module to control the on and off of the electrically controlled optical switch and the analog switch and the operation of the SLD light source, and calculates the output optical power, output optical wavelength thermal drift, and detector responsivity of the silicon photonic chip to be tested by receiving the voltage of the intensity detector and the silicon photonic chip detector to be tested. The present invention can realize the integrated test of three typical indicators of silicon-based optical chip output optical power, detector responsivity, and wavelength drift, ensure the test accuracy, and avoid the problem of inconsistency in the test environment caused by using multiple test equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical gyroscopes, and in particular relates to a device and method for testing characteristic parameters of a silicon photonic chip for a silicon photonic gyroscope. Background Art

[0002] With the development of technology and the expansion of fields, interferometric fiber gyroscopes are gradually developing in the direction of miniaturization and low cost. The miniaturization and low cost development of traditional fiber gyroscopes face huge challenges. The main limiting factor is that the optical path of traditional fiber gyroscopes contains multiple discrete optical devices, multiple melting points and multiple sections of pigtails that need to be processed, resulting in complex production processes, large volume, high cost and low yield of fiber gyroscopes. In recent years, silicon-based optical chips have made breakthroughs and have been widely used in the field of optical communications, providing new ideas for the integration and miniaturization of fiber gyroscopes: replacing the discrete optical devices of traditional fiber gyroscopes with silicon-based optical chips, its volume, weight, cost and power consumption will be greatly reduced, and silicon photonic gyroscopes have become an important development direction for gyro inertial devices.

[0003] Silicon-based optical chips are the core components of silicon photonic gyroscopes, and their performance directly affects the accuracy of the gyroscopes. From the current application, silicon-based optical chips generally have prominent problems such as weak output optical power, low detection response, and wavelength thermal drift. This will lead to low signal-to-noise ratio of silicon photonic gyroscopes, performance degradation, and affect the yield of silicon photonic gyroscopes. Therefore, it is urgent to test the characteristic parameters of silicon-based optical chips. Summary of the invention

[0004] In response to the demand for characteristic parameter testing of silicon-based optical chips, the present invention provides a device and method for testing characteristic parameters of silicon photonic chips for silicon photonic gyroscopes, which can realize integrated testing of three typical indicators of silicon-based optical chips: output optical power, detector responsiveness, and wavelength drift. By integrating an optical transceiver module with stable output optical power and constant detection responsiveness in the test device, the output optical power and detection response of the silicon photonic chip to be tested can be tested. By integrating an optical waveguide ring reference cavity and an intensity detector in the test device, wavelength thermal drift testing can be realized, thereby achieving the purpose of testing multiple parameters with the same test device.

[0005] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0006] The present invention provides a silicon photonic chip characteristic parameter testing device for a silicon photonic gyroscope, comprising:

[0007] The electrically controlled optical switch includes three input terminals, three test channels, and three output terminals which are connected in sequence. The input terminals are connected to the output pigtails of the silicon photonic chip to be tested, and the output terminals are connected to the optical signal input terminals of the analog switch. The three test channels are controlled on and off by the test and control module.

[0008] The analog switch comprises three optical signal input terminals, a light source input terminal, a light intensity output terminal, an optical signal output terminal and three optical fiber channels, wherein the three optical signal input terminals are connected to the light intensity output terminal through an optical fiber channel, the light intensity output terminal is connected to a first intensity detector, the three optical signal input terminals are connected to the optical signal output terminal through an optical fiber channel, the optical signal output terminal is sequentially connected to a reference cavity and a third intensity detector, the light source input terminal is connected to an SLD light source, the light source is transmitted to the three optical signal input terminals through an optical fiber channel, and then enters the electrically controlled optical switch in reverse direction;

[0009] The test and control module is used to control the on and off of the electrically controlled optical switch and the analog switch and the operation of the SLD light source, and is also used to receive the voltages of the first intensity detector, the third intensity detector and the detector of the silicon photonic chip to be tested, and calculate the output optical power, output optical wavelength thermal drift and detector responsivity of the silicon photonic chip to be tested;

[0010] The reference cavity includes a spiral optical waveguide of a certain length and is used to perform optical wavelength screening on input light.

[0011] Furthermore, the reference cavity adopts a double-layer stacking structure, the reference cavity includes a second layer of optical waveguide and a first layer of optical waveguide arranged up and down, the second layer of optical waveguide includes an input section optical waveguide, a plurality of turns of spiral optical waveguide and a top layer coupling region gradient structure located in the central area of ​​the spiral optical waveguide in sequence, the first layer of optical waveguide structure includes a bottom layer coupling region gradient structure located in the central area, a plurality of turns of spiral optical waveguide, and an output section optical waveguide in sequence, the top and bottom layer coupling region gradient structures are tapered optical waveguide structures with gradually decreasing widths, the structural central axes of the top and bottom layer coupling region gradient structures are located in the same vertical plane and are parallel up and down, the top and bottom layer coupling region gradient structures are arranged in opposite directions according to the tapered reduction direction, and a local area of ​​the top layer coupling region gradient structure is located directly above the bottom layer coupling region gradient structure.

[0012] Furthermore, the number of spiral turns of the second layer of optical waveguide and the first layer of optical waveguide is in the range of 20 to 200 turns; the spacing between adjacent optical waveguides in each layer is in the range of 50 to 200 microns, and the minimum bending radius is not less than 2 mm.

[0013] Furthermore, the ratio of the depth to the width of each layer of the optical waveguide is less than 0.1, the width ranges from 3 to 5 μm, and the depth ranges from 50 to 200 nm.

[0014] Furthermore, the overall value range of the gradient structure of the top layer and the bottom layer coupling region is 20-50 μm, and the value range of the narrowest width of the gradient structure of the top layer and the bottom layer coupling region is 400-800 nm.

[0015] Furthermore, the test and control module includes

[0016] An output optical power calculation module, used for receiving the voltage of the first intensity detector and calculating the output optical power;

[0017] An output light wavelength calculation module, used for receiving the voltage of the third intensity detector and calculating the thermal drift of the output light wavelength;

[0018] A responsivity calculation module is used to receive the voltage of the silicon photonic chip detector to be tested and calculate the responsivity of the detector;

[0019] Light source control module, used to control the temperature and driving current of the SLD light source;

[0020] Channel gating module, used to control the gating of three test channels of the electric-controlled optical switch;

[0021] The project selection module is used to control the selection of the three optical fiber channels of the analog switch to realize the selection of optical power, responsivity or optical wavelength thermal drift test items.

[0022] Furthermore, several output fiber pigtails of the silicon photonic chip to be tested are respectively connected to different input ends of the electrically controlled optical switch through a flange.

[0023] Furthermore, the silicon photonic chip characteristic parameter testing device for the silicon photonic gyroscope also includes three stabilized DC power supplies, which are respectively used to power the first intensity detector, the third intensity detector and the silicon photonic chip detector to be tested.

[0024] Furthermore, the silicon photonic chip characteristic parameter testing device for the silicon photonic gyroscope also includes

[0025] A first light source temperature driving module is connected to the SLD light source and is used to control a constant current and a constant temperature of the SLD light source;

[0026] The second light source temperature driving module is connected to the SLD light source of the silicon photonic chip to be tested, and is used to control the constant current and constant temperature of the silicon photonic chip to be tested.

[0027] The present invention also provides a method for testing characteristic parameters of a silicon photonic chip for a silicon photonic gyroscope, comprising the following steps:

[0028] Independently connect the pigtail of the silicon photonic chip to be tested to the input end of the electrically controlled optical switch;

[0029] Control the test channel gating of the electrically controlled optical switch;

[0030] Test items for controlling analog switchesFiber channel gating;

[0031] Conduct output optical power test, collect the measured voltage of the first intensity detector, and calculate the output optical power of the silicon photonic chip to be tested;

[0032] Conduct detector responsivity test, collect the measured voltage of the intensity detector of the silicon photonic chip to be tested, and calculate the detector responsivity of the silicon photonic chip to be tested;

[0033] Carry out wavelength thermal drift test, collect the measurement voltage of the third intensity detector, and calculate the output light wavelength thermal drift of the silicon photonic chip to be tested.

[0034] Furthermore, the calculation method of the output optical power of the silicon photonic chip to be tested is:

[0035] P out =V1 / (A1R f G1)

[0036] Where V1 is the measured voltage of the first intensity detector, A1 is the responsivity of the first intensity detector, R f is the transimpedance of the first intensity detector, G1 is the optical path attenuation coefficient from the silicon photonic chip to be tested to the first intensity detector;

[0037] The calculation method of the detector responsivity of the silicon photonic chip to be tested is:

[0038] A in =P in V2 / (R f G2)

[0039] Among them, V2 is the detection voltage of the intensity detector on the silicon photonic chip to be tested, R f is the transimpedance of the intensity detector on the silicon photonic chip, G2 is the optical path attenuation coefficient from the SLD light source to the intensity detector of the silicon photonic chip to be tested;

[0040] The calculation method of the thermal drift of the output light wavelength of the silicon photonic chip to be tested is:

[0041] Δλ out =(V3'-V3) / μ

[0042] Among them, μ is the voltage-wavelength coefficient of the reference cavity, V3 is the measured voltage of the third intensity detector, and V3' is the measured voltage of the third intensity detector after the silicon photonic chip to be tested has been working for a set time.

[0043] Furthermore, the voltage-wavelength coefficient of the reference cavity is determined by the following method:

[0044] The optical waveguide input end of the reference cavity is connected to a wavelength-tunable standard narrow-spectrum light source, and the optical waveguide output end of the reference cavity is connected to a wavelength meter;

[0045] Adjust the standard narrow spectrum light source to output narrow spectrum laser of set wavelength, and record the output voltage V of the straight section outside the resonance valley measured by the wavelength meter. 直 ;

[0046] Adjust the wavelength of the standard narrow spectrum light source until the output voltage of the wavelength meter is at the minimum value V 谷 ;

[0047] Unidirectionally adjust the wavelength of the standard narrow spectrum light source, record the voltage output and the corresponding light wavelength at different wavelengths in turn, and guide the output voltage to reach V 直 ;

[0048] A straight line fitting is performed based on the voltage output and the light wavelength, and the slope of the voltage versus wavelength is calculated to obtain the voltage-wavelength coefficient of the reference cavity.

[0049] Furthermore, the reference cavity is placed on a TEC refrigerator constant temperature control platform; the rate of unidirectionally adjusting the standard narrow spectrum light source is 0.1±0.01pm.

[0050] The beneficial effects of the present invention compared with the prior art are as follows:

[0051] The present invention provides a device and method for testing characteristic parameters of silicon photonic chips for silicon photonic gyroscopes, which can realize three typical index tests of silicon-based optical chip output optical power, detector responsivity, and wavelength drift. By integrating an optical transceiver module with stable output optical power and constant detection responsivity in the test device, the output optical power and detection response of the silicon photonic chip to be tested can be tested; by integrating an optical waveguide ring reference cavity and an intensity detector in the test device, the wavelength thermal drift test can be realized, so that the same test device can be used to test multiple parameters such as the output optical power, detector responsivity, and wavelength thermal drift of the silicon-based optical chip, thereby solving the problem of testing the characteristic parameters of the silicon-based optical chip, and further achieving the purpose of improving the performance and manufacturing yield of the silicon photonic gyroscope.

[0052] At the same time, the silicon photonic chip characteristic parameter device for the silicon photonic gyroscope integrates electrically controlled optical switches and analog switches, which can realize the testing and recording of multi-axis silicon photonic chips and flexibly adjust the test sequence. It has the technical advantages of simple structure, multiple test items and high test accuracy.

[0053] The present invention uses the same test device to complete the output optical power, detector responsivity, and wavelength thermal drift tests in batches, which can avoid installation errors and test environment errors caused by assembling silicon photonic chips on different test equipment (such as different heat generation and test errors in different test equipment), and ensure the consistency of the output optical power, detector responsivity, and wavelength drift tests.

[0054] The present invention adopts an optical waveguide annular reference cavity and an intensity detector to perform wavelength thermal drift test. Compared with the prior art that uses a wavelength meter to test wavelength drift, the present invention has the advantages of simple structure and low cost. At the same time, the wavelength drift test using the reference cavity has high wavelength resolution and a simple conversion calculation method, which meets the use requirements of a high-precision optical gyroscope.

[0055] The optical waveguide annular reference cavity designed by the present invention adopts a double-layer stacking structure, which can realize a longer optical waveguide under a smaller reference cavity size, achieve more accurate wavelength detection accuracy, and increase the loop length under a certain loss while ensuring a small structure size, thereby optimizing the wavelength resolution of the reference cavity. The minimum bending radius of the spiral optical waveguide in the present invention is not less than 2mm, ensuring that the reference cavity has a higher wavelength resolution; by optimizing the gradient structure parameters of the coupling zone, the interlayer coupling efficiency is achieved to reach more than 90%. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The included drawings are used to provide a further understanding of the embodiments of the present invention, which constitute a part of the specification, are used to illustrate the embodiments of the present invention, and together with the text description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0057] Figure 1 A schematic diagram of the composition of a device for testing characteristic parameters of a silicon photonic chip for a silicon photonic gyroscope provided in a specific embodiment of the present invention;

[0058] Figure 2 A schematic diagram of the composition of a test and control module provided in a specific embodiment of the present invention;

[0059] Figure 3 A schematic diagram of a double-layer stacked reference cavity structure provided in a specific embodiment of the present invention;

[0060] Figure 4 A schematic structural diagram of an optical waveguide tapered jump-layer structure provided by a specific embodiment of the present invention;

[0061] Figure 5 A schematic diagram of the optical path attenuation coefficient test principle provided by a specific embodiment of the present invention;

[0062] Figure 6 A schematic diagram of the voltage-wavelength coefficient calibration principle of a reference cavity provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0063] Specific embodiments of the present invention are described in detail below. In the following description, for the purpose of explanation and not limitation, specific details are set forth to help fully understand the present invention. However, it will be apparent to those skilled in the art that the present invention may also be practiced in other embodiments that depart from these specific details.

[0064] It should be noted that in order to avoid obscuring the present invention due to unnecessary details, only the device structure and / or processing steps closely related to the scheme of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0065] The present invention provides a silicon photonic chip characteristic parameter testing device for a silicon photonic gyroscope, such as Figure 1 As shown, it includes a main controller with FPGA as the core, which specifically includes the following parts:

[0066] The electrically controlled optical switch includes three input terminals, three test channels, and three output terminals which are connected in sequence. The input terminals are connected to the output pigtails of the silicon photonic chip to be tested, and the output terminals are connected to the optical signal input terminals of the analog switch. The three test channels are controlled on and off by the test and control module.

[0067] The analog switch comprises three optical signal input terminals, a light source input terminal, a light intensity output terminal, an optical signal output terminal and three optical fiber channels, wherein the three optical signal input terminals are connected to the light intensity output terminal through an optical fiber channel, the light intensity output terminal is connected to a first intensity detector, the three optical signal input terminals are connected to the optical signal output terminal through an optical fiber channel, the optical signal output terminal is sequentially connected to a reference cavity and a third intensity detector, the light source input terminal is connected to an SLD light source, the light source is transmitted to the three optical signal input terminals through an optical fiber channel, and then enters the electrically controlled optical switch in reverse direction;

[0068] The test and control module is used to control the on and off of the electrically controlled optical switch and the analog switch and the operation of the SLD light source, and is also used to receive the voltages of the first intensity detector, the third intensity detector and the detector of the silicon photonic chip to be tested, and calculate the output optical power, output optical wavelength thermal drift and detector responsivity of the silicon photonic chip to be tested;

[0069] The reference cavity includes a spiral optical waveguide of a certain length and is used to perform optical wavelength screening on input light.

[0070] Furthermore, several output fiber pigtails of the silicon photonic chip to be tested are respectively connected to different input ends of the electrically controlled optical switch through a flange.

[0071] Furthermore, the silicon photonic chip characteristic parameter testing device for the silicon photonic gyroscope also includes three stabilized DC power supplies, which are respectively used to power the first intensity detector, the third intensity detector and the silicon photonic chip detector to be tested.

[0072] Furthermore, the silicon photonic chip characteristic parameter testing device for the silicon photonic gyroscope includes, in order to stably control the operation of the SLD light source and the SLD light source of the silicon photonic chip to be tested,

[0073] The light source temperature driving module 1 is connected to the SLD light source and is used to control the constant current and constant temperature of the SLD light source;

[0074] The light source temperature driving module 2 is connected to the SLD light source of the silicon photonic chip to be tested, and is used to control the constant current and constant temperature of the silicon photonic chip to be tested.

[0075] Furthermore, the test and control module includes

[0076] An output optical power calculation module, used for receiving the voltage of the first intensity detector and calculating the output optical power;

[0077] An output light wavelength calculation module, used for receiving the voltage of the third intensity detector and calculating the thermal drift of the output light wavelength;

[0078] A responsivity calculation module is used to receive the voltage of the silicon photonic chip detector to be tested and calculate the responsivity of the detector;

[0079] Light source control module, used to control the temperature and driving current of the SLD light source;

[0080] Channel gating module, used to control the gating of three test channels of the electric-controlled optical switch;

[0081] The project selection module is used to control the selection of the three optical fiber channels of the analog switch to realize the selection of optical power, responsivity or optical wavelength thermal drift test items.

[0082] The structure of the test and control module is as follows Figure 2 As shown, FPGA is used as the control core, which specifically includes 3 calculation modules and 3 control modules. The 3 calculation modules calculate the optical power, responsivity and optical wavelength thermal drift of the output silicon photonic chip according to voltages V1, V2 and V3 respectively, and the 3 control modules control the temperature / driving current control of the SLD light source, the gating between multiple channels and the gating of test items (optical power, responsivity and optical wavelength).

[0083] Furthermore, in order to reduce the volume of the test device, the reference cavity adopts a double-layer stacking structure, the reference cavity includes a second layer of optical waveguide and a first layer of optical waveguide arranged up and down, the second layer of optical waveguide includes a straight input section optical waveguide, a plurality of spiral optical waveguides coiled from the outside to the inside in a plane, and a top layer coupling zone gradient structure located in the central area of ​​the spiral optical waveguide in sequence, the first layer of optical waveguide structure includes a bottom layer coupling zone gradient structure located in the central area, a plurality of spiral optical waveguides coiled from the inside to the outside in a plane, and a straight output section optical waveguide in sequence, the top and bottom layer coupling zone gradient structures are tapered optical waveguide structures with gradually decreasing widths, the structural central axes of the top and bottom layer coupling zone gradient structures are located in the same vertical plane and are parallel up and down, the top and bottom layer coupling zone gradient structures are arranged in opposite directions according to the tapered reduction direction, and a local area of ​​the top layer coupling zone gradient structure is located directly above the bottom layer coupling zone gradient structure, forming an optical waveguide tapered jump layer structure.

[0084] Double-layer stacked structure reference cavity Figure 3 As shown, the reference cavity is made of different optical waveguide materials (LiNbO3, SiN, Si, etc.). The number of turns of a double-layer reference cavity is determined by the transmission loss of the optical waveguide material, preferably 20-200 turns, and the spacing between each layer of optical waveguide is 50-500 microns. In the double-layer stacked reference cavity, light first enters the reference cavity from the P1 port of the second layer of optical waveguide, and reaches the central interface of the spiral coil after being transmitted through the spiral coil in the second layer of optical waveguide. The minimum bending radius of the central interface is not less than 2mm to ensure that the bending loss of the SiN optical waveguide is negligible, thereby ensuring that the reference cavity has a high wavelength resolution. The optical path connection between the second layer and the first layer of optical waveguide is realized through the optical waveguide tapered jump layer structure, and the output port P2 is reached through the spiral coil of the first layer of optical waveguide. Therefore, compared with the traditional single-turn reference cavity, this technical solution can double the length of the optical waveguide reference cavity, and can achieve a longer (>10m) reference cavity under a smaller reference cavity size (usually less than 1cm), thereby achieving more accurate wavelength detection accuracy.

[0085] The optical waveguide tapered jump layer structure is as follows Figure 4 As shown, it specifically includes a bottom optical waveguide and a coupling zone gradient structure, a top optical waveguide and a coupling zone gradient structure, wherein the bottom optical waveguide and the top optical waveguide are designed to have a small depth-to-width ratio. Preferably, the depth-to-width ratio of the bottom optical waveguide or the top optical waveguide is below 0.1, so as to reduce the scattering loss of the optical waveguide sidewall. Preferably, the width W1 and W2 of each layer of the optical waveguide core layer are designed to be 3-5μm, and the depth H1 and H2 are 50-200nm. The width of the gradient structure of the top and bottom coupling zones gradually decreases from W1 or W2, and the length z of the entire coupling zone is designed to be 20-50μm, and the width at the narrowest point ranges from 400-800nm. By simulating and optimizing the overlapping areas of the gradient structures of the top and bottom coupling zones and the structural parameters of the entire coupling zone, the interlayer coupling efficiency is increased to more than 90%, thereby increasing the loop length under a certain loss, thereby ensuring that the reference cavity has a high wavelength resolution.

[0086] The present invention provides a silicon photonic chip characteristic parameter testing device for a silicon photonic gyroscope, the main functions of which are as follows:

[0087] 1) An intensity detector 1 is integrated for testing the output optical power of the silicon photonic chip to be tested;

[0088] 2) Ability to implement detector responsivity test according to the output voltage of intensity detector 2 in the silicon photonic chip to be tested;

[0089] 3) The reference cavity and intensity detector 3 are integrated for the wavelength drift test of the silicon photonic chip to be tested;

[0090] 4) An electrically controlled optical switch is integrated to enable selection and switching between test channels 1, 2, and 3;

[0091] 5) Integrated analog switch can realize test item selection and switching.

[0092] The present invention also provides a method for testing characteristic parameters of a silicon photonic chip for a silicon photonic gyroscope, comprising the following steps:

[0093] 1) Optical path connection: According to the number of channels of the silicon photonic chip, its output fiber pigtail is connected through the corresponding flange to enter the silicon photonic chip characteristic parameter test device. If it is a single channel, the single fiber pigtail is inserted into flange 1. If it is a dual channel, the two fiber pigtail outputs are inserted into flange 1 and flange 2 in turn. If it is a triple channel, the three fiber pigtail outputs are inserted into flange 1, flange 2 and flange 3 in turn.

[0094] 2) Channel selection: According to the test instruction, the test and control module outputs the channel selection command to select the corresponding channel to be tested, as follows: "00" represents no test, "01" represents test channel 1, "10" represents test channel 2, and "11" represents test channel 3.

[0095] 3) Test item selection: According to the test instructions, the test and control module outputs the item selection command, as follows: "00" represents no test, "01" represents test output optical power, "10" represents test detector responsivity, and "11" represents test wavelength drift.

[0096] 4) Output optical power test:

[0097] The light source temperature driving module 2 starts working, providing constant current and constant temperature control for the silicon photonic chip to be tested. At this time, the output light of the silicon photonic chip to be tested enters the electrically controlled optical switch through the flange 1, and then enters the intensity detector 1 through the analog switch. After the regulated DC power supply 1 supplies power to the intensity detector 1, it directly outputs the voltage V1 in it. The output optical power P of the silicon photonic chip to be tested is calculated by the following formula: out for:

[0098] P out =V1 / (A1R f G1) (1)

[0099] Wherein, V1 is the detection voltage of the first intensity detector, A1 is the responsivity of the first intensity detector, R f is the transimpedance of the first intensity detector, and G1 is the optical path attenuation coefficient from the silicon photonic chip to be tested to the first intensity detector.

[0100] The method for determining the value of G1 is as follows:

[0101] like Figure 5As shown in the figure, point A1 is connected to the light source, point B is connected to the optical power meter, and the output optical power of different light sources is set to P Ai (i represents different power points, which are determined by the setting power of the light source and are usually not less than 10 times when the output power is less than 1mW). Record the optical power values ​​detected by the optical power meter at different power points, recorded as P Bi , with P Bi is the Y coordinate, P Ai As the X coordinate, perform YX linear fitting to obtain the fitting slope, which is the optical path attenuation coefficient G1 from the silicon photonic chip to be tested to the first intensity detector.

[0102] The optical path attenuation coefficient G1 is specifically expressed as:

[0103] G1=P Bi / P Ai (2)

[0104] Among them, P Ai is the light source output power at the i-th power point, P Bi is the optical power value detected by the optical power meter at the i-th power point, where i represents a different power point.

[0105] 5) Detector responsivity test:

[0106] The light source temperature driving module 1 starts working, providing the SLD light source with constant current and constant temperature control, generating a stable light output. The output light power is recorded as P in , and then enters the electrically controlled optical switch through the analog switch. The optical switch has bidirectional transmission characteristics. The light enters the silicon photonic chip to be tested through the corresponding flange. At this time, the regulated DC power supply 2 is turned on to power the optical detector on the silicon photonic chip to be tested, and the output is a voltage V2. The detector responsivity A of the silicon photonic chip to be tested is calculated by the following formula: in for:

[0107] A in =P in V2 / (R f G2) (3)

[0108] Among them, V2 is the detection voltage of the intensity detector on the silicon photonic chip to be tested, R f is the transimpedance of the intensity detector on the silicon photonic chip, and G2 is the optical path attenuation coefficient from the SLD light source to the intensity detector on the silicon photonic chip to be tested.

[0109] The method for determining the value of the optical path attenuation coefficient G2 is as follows:

[0110] Figure 5 Point A1 is connected to the optical power meter, point B is connected to the light source, and the output optical power of different light sources is set to P' Aj(j is a different power point, which is determined by the setting power of the light source and is usually not less than 10 times when the output power is less than 1mW). Record the optical power value detected by the optical power meter at different power points and record it as P' Bj , with P' Bj is the Y coordinate, P' Aj As the X coordinate, perform YX linear fitting to get the fitting slope, which is the optical path attenuation coefficient G2 from the SLD light source to the intensity detector of the silicon photonic chip to be tested.

[0111] 6) Wavelength drift test:

[0112] The light source temperature driving module 2 starts working, providing constant current and constant temperature control for the silicon photonic chip to be tested. At this time, the output light of the silicon photonic chip to be tested enters the electrically controlled optical switch through the flange 1, and then enters the double-layer stacked structure reference cavity through the analog switch, and then enters the intensity detector 3. The regulated DC power supply controls the power supply of the intensity detector 3. At this time, the light intensity of the silicon photonic chip to be tested will be output in the form of voltage V3 and enter the test and control module. Every 10 minutes (the actual test time can be hardware controlled by FPGA), the output voltage V3' is collected once. According to the voltage before and after 10 minutes, the output light wavelength thermal drift Δλ of the silicon photonic chip to be tested is calculated by the following formula out for:

[0113] Δλ out =(V3'-V3) / μ (4)

[0114] Wherein, μ is the voltage-wavelength coefficient of the reference cavity, which is obtained by previous calibration. The calibration device is as follows: Figure 5 As shown, it specifically includes a standard narrow-spectrum light source with tunable wavelength, a reference cavity placed on a constant temperature control platform of a TEC refrigerator, and a wavelength meter with coupled output. The optical waveguide input end and output end of the reference cavity are respectively connected to the standard narrow-spectrum light source and the wavelength meter. The wavelength meter has the functions of optical power detection and optical wavelength direct reading in the form of voltage output.

[0115] The specific calibration process of the voltage-wavelength coefficient of the reference cavity is as follows:

[0116] ① Standard narrow spectrum light source inputs narrow spectrum laser of a certain wavelength;

[0117] ②TEC cooler realizes constant temperature control of the reference cavity, and the temperature control accuracy is better than 0.001℃, ensuring the stable operation of the reference cavity. At this time, the voltage output of the wavelength meter is a straight section output outside the resonance valley, recorded as V 直 ;

[0118] ③ Adjust the wavelength of the standard narrow spectrum light source until the output voltage of the wavelength meter is at the minimum value V 谷 , at this time record the first wavelength λ read by the wavelength meter;

[0119] ④Unidirectionally adjust the wavelength of the standard narrow spectrum light source at a rate of 0.1±0.01pm (i.e., starting from the first wavelength λ, unidirectionally increase or decrease the output wavelength of the standard narrow spectrum light source), and record the voltage output V at different wavelengths in turn. a 、V b 、V c ...and the wavelength λ of the light at the corresponding time a , b , c , until the voltage reaches V 直 The wavelength of light is no longer recorded;

[0120] ⑤According to the measured voltage data V a 、V b 、V c ...and the optical wavelength data λ a , b , c …Perform a straight line fit and calculate the slope of voltage versus wavelength to obtain the voltage-wavelength coefficient μ of the reference cavity, in V / nm.

[0121] Features described and / or illustrated above for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or used in place of features in other embodiments.

[0122] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps, components or combinations thereof.

[0123] The many features and advantages of these embodiments are apparent from this detailed description, and thus the appended claims are intended to cover all such features and advantages of these embodiments that fall within their true spirit and scope. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not intended that the embodiments of the invention be limited to the exact construction and operation illustrated and described, but rather all suitable modifications and equivalents falling within the scope thereof are intended to be covered.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0125] Parts of the present invention that are not described in detail are well known to those skilled in the art.

Claims

1. A silicon photonic chip characteristic parameter testing device for a silicon photonic gyroscope, characterized in that: include The electrically controlled optical switch includes three input terminals, three test channels, and three output terminals which are connected in sequence. The input terminals are connected to the output pigtails of the silicon photonic chip to be tested, and the output terminals are connected to the optical signal input terminals of the analog switch. The three test channels are controlled on and off by the test and control module. The analog switch comprises three optical signal input terminals, a light source input terminal, a light intensity output terminal, an optical signal output terminal and three optical fiber channels, wherein the three optical signal input terminals are connected to the light intensity output terminal through an optical fiber channel, the light intensity output terminal is connected to a first intensity detector, the three optical signal input terminals are connected to the optical signal output terminal through an optical fiber channel, the optical signal output terminal is sequentially connected to a reference cavity and a third intensity detector, the light source input terminal is connected to an SLD light source, the light source is transmitted to the three optical signal input terminals through an optical fiber channel, and then enters the electrically controlled optical switch in reverse direction; The test and control module is used to control the on and off of the electrically controlled optical switch and the analog switch and the operation of the SLD light source, and is also used to receive the voltages of the first intensity detector, the third intensity detector and the detector of the silicon photonic chip to be tested, and calculate the output optical power, output optical wavelength thermal drift and detector responsivity of the silicon photonic chip to be tested; A reference cavity, including a spiral optical waveguide of a certain length, for performing optical wavelength screening on input light; The reference cavity adopts a double-layer stacking structure, and the reference cavity includes a second layer of optical waveguide and a first layer of optical waveguide arranged up and down, the second layer of optical waveguide includes an input section optical waveguide, a plurality of turns of spiral optical waveguides, and a top layer coupling region gradient structure located in the central area of ​​the spiral optical waveguide in sequence, the first layer of optical waveguide structure includes a bottom layer coupling region gradient structure located in the central area, a plurality of turns of spiral optical waveguides, and an output section optical waveguide in sequence, the top layer and bottom layer coupling region gradient structures are tapered optical waveguide structures with gradually decreasing widths, the structural central axes of the top layer and bottom layer coupling region gradient structures are located in the same vertical plane and are parallel up and down, the top layer and bottom layer coupling region gradient structures are arranged in opposite directions according to the tapered reduction direction, and a local area of ​​the top layer coupling region gradient structure is located directly above the bottom layer coupling region gradient structure.

2. The characteristic parameter testing device according to claim 1, characterized in that: The number of spiral turns of the second layer of optical waveguide and the first layer of optical waveguide is in the range of 20 to 200 turns; the spacing between adjacent optical waveguides in each layer is 50 to 200 microns, and the minimum bending radius is not less than 2 mm; the depth to width ratio of each layer of optical waveguide is less than 0.1, the width is in the range of 3-5 μm, and the depth is in the range of 50-200 nm.

3. The characteristic parameter testing device according to claim 1, characterized in that: The overall value range of the gradient structure of the top layer and bottom layer coupling regions is 20-50 μm, and the value range of the narrowest width of the gradient structure of the top layer and bottom layer coupling regions is 400-800 nm.

4. The characteristic parameter testing device according to claim 1, characterized in that: The test and control module includes An output optical power calculation module, used for receiving the voltage of the first intensity detector and calculating the output optical power; An output light wavelength calculation module, used for receiving the voltage of the third intensity detector and calculating the thermal drift of the output light wavelength; A responsivity calculation module is used to receive the voltage of the silicon photonic chip detector to be tested and calculate the responsivity of the detector; Light source control module, used to control the temperature and driving current of the SLD light source; Channel gating module, used to control the gating of three test channels of the electric-controlled optical switch; The project selection module is used to control the selection of the three optical fiber channels of the analog switch to realize the selection of optical power, responsivity or optical wavelength thermal drift test items.

5. The characteristic parameter testing device according to claim 1, characterized in that: Several output fiber pigtails of the silicon photonic chip to be tested are connected to different input ends of the electrically controlled optical switch through a flange respectively; The silicon photonic chip characteristic parameter testing device for the silicon photonic gyroscope also includes three stabilized DC power supplies, which are respectively used to power the first intensity detector, the third intensity detector and the silicon photonic chip detector to be tested.

6. The characteristic parameter testing device according to claim 1, characterized in that: Also includes A first light source temperature driving module is connected to the SLD light source and is used to control a constant current and a constant temperature of the SLD light source; The second light source temperature driving module is connected to the SLD light source of the silicon photonic chip to be tested, and is used to control the constant current and constant temperature of the silicon photonic chip to be tested.

7. A method for testing characteristic parameters of a silicon photonic chip for a silicon photonic gyroscope, characterized in that: Using the characteristic parameter testing device according to any one of claims 1 to 6, the characteristic parameter testing method comprises the following steps: Connect the pigtails of the silicon photonic chip to be tested to one input end of the electrically controlled optical switch; Control the test channel gating of the electrically controlled optical switch; Test items for controlling analog switchesFiber channel gating; Conduct output optical power test, collect the measured voltage of the first intensity detector, and calculate the output optical power of the silicon photonic chip to be tested; Conduct detector responsivity test, collect the measured voltage of the intensity detector of the silicon photonic chip to be tested, and calculate the detector responsivity of the silicon photonic chip to be tested; Carry out wavelength thermal drift test, collect the measurement voltage of the third intensity detector, and calculate the output light wavelength thermal drift of the silicon photonic chip to be tested.

8. The characteristic parameter testing method according to claim 7, characterized in that: The calculation method of the output optical power of the silicon photonic chip to be tested is: P out =V1 / (A1R f G1) Where V1 is the measured voltage of the first intensity detector, A1 is the responsivity of the first intensity detector, R f is the transimpedance of the first intensity detector, G1 is the optical path attenuation coefficient from the silicon photonic chip to be tested to the first intensity detector; The calculation method of the detector responsivity of the silicon photonic chip to be tested is: A in =P in V2 / (R f G2) Among them, V2 is the detection voltage of the intensity detector on the silicon photonic chip to be tested, R f is the transimpedance of the intensity detector on the silicon photonic chip, G2 is the optical path attenuation coefficient from the SLD light source to the intensity detector of the silicon photonic chip to be tested; The calculation method of the thermal drift of the output light wavelength of the silicon photonic chip to be tested is: Dl out =(V3'-V3) / μ Among them, μ is the voltage-wavelength coefficient of the reference cavity, V3 is the measured voltage of the third intensity detector, and V3' is the measured voltage of the third intensity detector after the silicon photonic chip to be tested has been working for a set time.

9. The characteristic parameter testing method according to claim 8, characterized in that: The voltage-wavelength coefficient of the reference cavity is determined by the following method: The optical waveguide input end of the reference cavity is connected to a wavelength-tunable standard narrow-spectrum light source, and the optical waveguide output end of the reference cavity is connected to a wavelength meter; Adjust the standard narrow spectrum light source to output narrow spectrum laser of set wavelength, and record the output voltage V of the straight section outside the resonance valley measured by the wavelength meter. 直 ; Adjust the wavelength of the standard narrow spectrum light source until the output voltage of the wavelength meter is at the minimum value V 谷 ; Unidirectionally adjust the wavelength of the standard narrow spectrum light source, record the voltage output and the corresponding light wavelength at different wavelengths in turn, and guide the output voltage to reach V 直 ; A straight line fitting is performed based on the voltage output and the light wavelength, and the slope of the voltage versus wavelength is calculated to obtain the voltage-wavelength coefficient of the reference cavity.

10. The characteristic parameter testing method according to claim 9, characterized in that: The reference cavity is placed on a TEC refrigerator constant temperature control platform; the rate of unidirectionally adjusting the standard narrow spectrum light source is 0.1±0.01pm.

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