Silicon photonic gyroscope channel crosstalk suppression method and device based on difference frequency modulation and demodulation

Abstract

The present invention provides a method and device for suppressing channel crosstalk of a silicon photonic gyroscope based on difference frequency modulation and demodulation, including designing square wave modulation signals of each axial phase modulator, if the silicon photonic gyroscope is not larger than three axes, the frequencies of the square wave modulation signals of each axis are different, if the silicon photonic gyroscope is larger than three axes, the frequencies of the square wave modulation signals of at least two adjacent axes are different; according to the frequency of the square wave modulation signals of each axial phase modulator, the length of the axial optical fiber loop is set; the silicon photonic gyroscope light source is adjusted to work at constant temperature and constant current; the corresponding square wave modulation signals are applied to the phase modulators of each axis; the output signals of each axial detector are digitally correlated and detected using the square wave modulation signals of the axis, and the rotation speed of each axis is demodulated. The present invention avoids the influence of axial channel crosstalk on the main axis interference signal in the time domain by setting the modulation signals and loop length of each axis of the multi-axis silicon photonic gyroscope, thereby greatly improving the accuracy of the silicon photonic gyroscope.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical gyroscopes, and in particular relates to a method and a device for suppressing channel crosstalk of a silicon photonic gyroscope based on difference frequency modulation and demodulation. Background Art

[0002] With the development of technology and the expansion of fields, interferometric fiber gyroscopes are gradually developing towards 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 multi-axis (two-axis, three-axis, etc.) fiber gyroscopes contains multiple discrete optical devices, as many as more than ten melting points and pigtails need to be processed, resulting in complex processes, large volumes, high costs, and low yields for medium and low precision three-axis fiber gyroscopes. In recent years, silicon-based integrated optical chips have made breakthroughs and have been widely used in the field of communications, providing a new idea for the integration and miniaturization of fiber gyroscopes: replacing the discrete optical devices in traditional fiber gyroscopes with integrated optical chips, its volume, weight, cost, power consumption, etc. will be greatly reduced, and silicon photonic gyroscopes have become an important development direction for inertial devices.

[0003] In a multi-axis silicon photonic gyroscope, multiple detectors are integrated onto a single optical chip. Compared with the traditional discrete detector solution, it has the advantages of small size, low cost, and easy production. However, the on-chip integration of multiple detectors will also bring about channel crosstalk problems, resulting in reduced gyroscope accuracy. Studies have shown that the multi-channel crosstalk of integrated optical devices can cause the gyroscope accuracy to deteriorate by 2 to 3 times, which is also the main difficulty in achieving high precision for multi-axis silicon photonic gyroscopes. In response to the above needs, it is urgent to propose a technical approach that can effectively suppress the channel crosstalk of silicon photonic gyroscopes and improve accuracy. Summary of the invention

[0004] In view of the technical problem of gyroscope channel crosstalk in the prior art multi-axis silicon photonic gyroscope, the present invention proposes a method and device for suppressing silicon photonic gyroscope channel crosstalk based on difference frequency modulation and demodulation.

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

[0006] As one aspect of the present invention, a method for suppressing channel crosstalk of a silicon photonic gyroscope based on difference frequency modulation and demodulation is provided, wherein the silicon photonic gyroscope comprises at least two axes, each axis corresponds to a channel, and at least a detector of each channel is integrated on the chip of the silicon photonic gyroscope. The method for suppressing channel crosstalk of the silicon photonic gyroscope comprises the following steps:

[0007] Designing square wave modulation signals of each axial phase modulator, if the silicon photonic gyroscope is not larger than three axes, the frequencies of the square wave modulation signals of each axis are different; if the silicon photonic gyroscope is larger than three axes, the frequencies of the square wave modulation signals of at least two adjacent axes are different;

[0008] According to the frequency of the square wave modulation signal of each axial phase modulator, the length of the axial optical fiber loop is set;

[0009] Adjust the silicon photonic gyroscope light source to operate at constant temperature and constant current;

[0010] Applying a corresponding square wave modulation signal to the phase modulator of each axis;

[0011] For each axial detector output signal, digital correlation detection is performed using the axial square wave modulation signal to demodulate the rotation speed of each axial direction.

[0012] Furthermore, the frequency design method of the square wave modulation signal is as follows:

[0013] The silicon photonic gyroscope has two axes, and the modulation frequencies of the two axes are designed to be: f0, 2f0 respectively, and the lengths of the optical fiber loops of the two axes are correspondingly designed to be: c / 2nf0, c / 4nf0, where f0 represents the reference frequency, c is the speed of light in vacuum, and n is the refractive index of the optical fiber;

[0014] The silicon photonic gyroscope has three axes, which are arranged in the order of X-axis, Y-axis and Z-axis. The modulation frequencies of the X-axis, Y-axis and Z-axis are designed to be 9f0 / 10, 2f0 and 11f0 / 10 respectively. The lengths of the optical fiber loops of the X-axis, Y-axis and Z-axis are designed to be 5c / 9nf0, c / 4nf0 and 5c / 11nf0 respectively.

[0015] The silicon photonic gyroscope includes more than four axes, and the modulation frequencies of the axes arranged in sequence are cyclically arranged according to the rules of 9f0 / 10, 2f0, 11f0 / 10, and 2f0; the length of each axial optical fiber loop is:

[0016] L i =c / 2nf i

[0017] Where i represents a certain axis of the silicon photonic gyroscope, and f i Indicates the frequency of the square wave modulation signal on the i-axis.

[0018] Furthermore, the amplitude of the square wave modulation signal is the half-wave voltage of its corresponding axial phase modulator.

[0019] Furthermore, the silicon photonic gyroscope channel crosstalk suppression method further includes the following steps:

[0020] The closed-loop feedback signal caused by each axial speed is calculated and superimposed on each axial square wave modulation signal to perform closed-loop feedback control.

[0021] Furthermore, the closed-loop feedback signal is a step wave, and the step width of the step wave is:

[0022] Tstep_i =nL i / c

[0023] Among them, T step_i It is represented by the step width of the step wave of the closed-loop feedback signal caused by the i-axis speed, i represents a certain axis of the silicon photonic gyroscope, L i It is expressed as the length of the fiber loop on the i-axis, c is the speed of light in a vacuum, and n is the refractive index of the fiber;

[0024] The step height of the step wave is:

[0025] H step_i (t) = K tp_i V pp_i D out_i (t) / 2 N

[0026] Among them, H step_i (t) is the step height of the step wave of the closed-loop feedback signal caused by the i-axis speed at time t; N is the number of bits of the DAC generating the step wave; K tp_i is the modulation coefficient of the i-axis phase modulator; D out_i (t) is the speed of the demodulated output of axis i at time t; V pp_i is the half-wave voltage of the i-axis phase modulator.

[0027] As another aspect of the present invention, a silicon photonic gyroscope channel crosstalk suppression device based on difference frequency modulation and demodulation is provided, wherein the silicon photonic gyroscope includes at least two axes, each axis corresponds to a channel, and at least a detector of each channel is integrated on the chip of the silicon photonic gyroscope. The silicon photonic gyroscope channel crosstalk suppression device includes a gyroscope signal detection and crosstalk suppression circuit, and the gyroscope signal detection and crosstalk suppression circuit includes a difference frequency modulation and demodulation module, a constant temperature and constant current control module, and a communication interface. The difference frequency modulation and demodulation module is used to generate square wave modulation signals of different frequencies and apply them to phase modulators of different axes of the silicon photonic gyroscope, and to collect the output signals of the detectors of each axis of the silicon photonic gyroscope, and demodulate the rotation speed of the corresponding axis; the constant temperature and constant current control module is used to control the constant temperature and constant current operation of the light source of the silicon photonic gyroscope, so that the light power of the light source is stably output; and the communication interface is used to communicate with a host computer.

[0028] Furthermore, the difference frequency modulation and demodulation module also calculates the closed-loop feedback signal caused by the rotational speed of each axial direction, and superimposes it on the square wave modulation signal of each axial direction to perform closed-loop feedback control.

[0029] Furthermore, the difference frequency modulation and demodulation module includes a group of signal generators and phase-sensitive detectors corresponding to each axis, the signal generator is used to generate a square wave modulation signal of the corresponding axis and a closed-loop feedback signal caused by the rotational speed, and the phase-sensitive detector is used to detect the phase deviation of the corresponding axis and output the rotational speed information.

[0030] The beneficial effects of the present invention compared with the prior art are as follows:

[0031] The present invention proposes a method and device for suppressing channel crosstalk of silicon photonic gyroscope based on difference frequency modulation and demodulation. The design adopts axial rings of different lengths. In modulation, square wave modulation signals are first used. The gyroscope interference signal is modulated to a high frequency band with low noise power density through carrier migration, which effectively avoids flicker noise in the low frequency band. In addition, square wave modulation signals of different frequencies are used. In demodulation, the speed demodulation of gyroscopes with different axes is realized based on the difference frequency scheme. Therefore, the influence of axial channel crosstalk on the main axis interference signal in the time domain can be effectively avoided, thereby greatly improving the accuracy of silicon photonic gyroscope. The silicon photonic gyroscope adopting this scheme has the technical characteristics of high accuracy and stable performance.

[0032] The silicon photonic gyroscope channel crosstalk suppression method provided by the present invention is simple to implement, easy to apply in engineering, and suitable for mass production of silicon photonic gyroscope integrated optical chips.

[0033] The present invention designs a closed-loop feedback signal caused by each axial rotation speed, and improves the dynamic response capability of the silicon photonic gyroscope through feedback control. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 Schematic diagram of the crosstalk suppression principle of the silicon photonic gyroscope channel provided by a specific embodiment of the present invention, (a) and (b) are the detector output and frequency response under the same frequency modulation and demodulation scheme, and (c) and (d) are the detector output and frequency response under the difference frequency modulation and demodulation scheme;

[0036] Figure 2 A schematic diagram of the structure of a three-axis silicon photonic gyroscope provided in a specific embodiment of the present invention;

[0037] Figure 3 A schematic diagram of the structure of a silicon photonic gyroscope difference frequency modulation and demodulation module provided in a specific embodiment of the present invention;

[0038] Figure 4 A schematic diagram of a step wave signal of a silicon photonic gyroscope closed-loop feedback signal provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] The crosstalk generation principle of silicon photonic chips is as follows Figure 1 As shown in the figure: For a three-axis silicon photonic gyroscope, detectors 1, 2, and 3 are integrated on a single silicon-based optical chip. Due to the close physical spacing, after the closed loop is successful, the main signal of the X-axis will be injected into the Y-axis sampling interval, forming X-axis crosstalk; similarly, the main signal of the Y-axis will also be injected into the X-axis sampling interval, forming Y-axis crosstalk. Similarly, the main signal of the Z-axis will also affect the X-axis and Y-axis. From the perspective of the time domain, the silicon photonic gyroscope based on digital sampling will inevitably sample the crosstalk into the useful signal during the signal processing process, such as Figure 1 (a) As shown; from the frequency domain, since the square wave demodulation is based on the digital phase-sensitive detection structure, its amplitude-frequency response curve is as follows Figure 1 As shown in (b), since the transmission spectrum of the response curve completely coincides with the spectrum of the crosstalk signal (both are odd harmonic components of the modulation frequency f0), the crosstalk signal is able to completely pass through the digital phase-sensitive detector during this process, making it impossible to suppress the crosstalk noise.

[0042] To address the crosstalk problem, the present invention proposes a method for suppressing crosstalk in silicon photonic gyroscope channels by difference frequency modulation and demodulation, using X, Y and Z axial rings of different lengths, and firstly using a square wave modulation signal in modulation to modulate the gyroscope interference signal to a high frequency band with low noise power density, thereby effectively avoiding flicker noise in the low frequency band; since square wave modulation signals of different frequencies are used, the speed demodulation of gyroscopes with different axes is achieved based on the difference frequency scheme in demodulation, thereby effectively avoiding the influence of axial channel crosstalk on the main axis interference signal in the time domain, thereby greatly improving the accuracy of the silicon photonic gyroscope.

[0043] Taking the X and Y axes as an example, the crosstalk signals between the X and Y axes are as follows: Figure 1 As shown in (c), the phase modulators of the X-axis and Y-axis will be subjected to the frequency f X 、f YThe square wave modulation of the two signals has a modulation frequency difference of D f , then the crosstalk frequency received on the Y axis is f X , and the demodulation frequency of the Y axis is f Y , there is also D f The frequency deviation of the crosstalk signal cannot affect the main interference signal through the digital phase-sensitive detector, so the channel crosstalk noise can be effectively suppressed.

[0044] As an embodiment of the present invention, a method for suppressing channel crosstalk of a silicon photonic gyroscope based on difference frequency modulation and demodulation is provided, wherein the silicon photonic gyroscope includes at least two axes, each axis corresponds to a channel, and the silicon photonic gyroscope chip has at least one detector for each channel integrated thereon. The method for suppressing channel crosstalk of a silicon photonic gyroscope includes the following steps:

[0045] Designing square wave modulation signals of each axial phase modulator, if the silicon photonic gyroscope is not larger than three axes (i.e., two axes or three axes), the frequencies of the square wave modulation signals of each axis are different; if the silicon photonic gyroscope is larger than three axes, the frequencies of the square wave modulation signals of at least two adjacent axes are different;

[0046] According to the frequency of the square wave modulation signal of each axial phase modulator, the length of the axial optical fiber loop is set;

[0047] Adjust the silicon photonic gyroscope light source to operate at constant temperature and constant current;

[0048] Applying a corresponding square wave modulation signal to the phase modulator of each axis;

[0049] For each axial detector output signal, digital correlation detection is performed using the axial square wave modulation signal to demodulate the rotation speed of each axial direction.

[0050] The present invention uses a difference frequency modulation signal to modulate and demodulate optical signals in different channels of a silicon photonic gyroscope, effectively avoiding the influence of axial channel crosstalk on the main axis interference signal in the time domain, thereby greatly improving the accuracy of the silicon photonic gyroscope. The channel crosstalk suppression method is simple to implement, easy to apply in engineering, and suitable for the production and manufacturing of integrated optical chips for silicon photonic gyroscopes in batches.

[0051] As another embodiment of the present invention, taking a three-axis silicon photonic gyroscope as an example, a method and device for suppressing channel crosstalk of a silicon photonic gyroscope based on difference frequency modulation and demodulation are provided.

[0052] The structure of the three-axis silicon photonic gyroscope is as follows: Figure 2 As shown, it mainly includes three parts: a three-axis silicon photonic chip, an X / Y / Z-axis optical fiber ring, and a gyroscope signal detection and crosstalk suppression circuit.

[0053] Among them, the three-axis silicon photonic chip integrates 1 light source, 3 detectors, 7 couplers and 3 phase modulators. The light source is connected to the input end of the 1×3 coupler. Each output end of the 1×3 coupler is connected to a 2×1 coupler, a filtering bending waveguide, a 1×2 coupler, and a phase modulator in sequence. The other output end of each 2×1 coupler is connected to a detector. The three-axis silicon photonic chip as a whole forms three optical signal channels of the X, Y, and Z axes. Due to the small detector channel spacing, the channel crosstalk is aggravated. In this embodiment, the phase modulator is a Y waveguide phase modulator.

[0054] The X-axis, Y-axis and Z-axis optical fiber loops are respectively connected to three phase modulators to realize rotation speed sensitivity in three orthogonal directions. In the present invention, the lengths of the three optical fiber loops are different corresponding to the different square wave modulation signals of the three axes.

[0055] The specific functions of the gyroscope signal detection and crosstalk suppression circuit are as follows:

[0056] (1) Perform difference frequency modulation to generate frequencies f X 、f Y 、f Z The square wave modulation signal acts on the phase modulators of the X-axis, Y-axis and Z-axis respectively, f X 、f Y 、f Z The three frequencies have different values;

[0057] (2) Perform difference frequency demodulation, respectively with frequency f X 、f Y 、f Z Perform digital correlation detection to demodulate the rotation speed of the X-axis, Y-axis and Z-axis;

[0058] (3) Control the constant temperature and current of the light source on the silicon photonic chip to achieve stable optical power output;

[0059] (4) Perform communication function and send the gyro data demodulated by difference frequency to the host computer through the transceiver chip.

[0060] Specifically, in order to achieve the above functions, in this embodiment, the gyroscope signal detection and crosstalk suppression circuit includes a difference frequency modulation and demodulation module, a constant temperature and constant current control module, and a communication interface. The difference frequency modulation and demodulation module is used to generate square wave modulation signals of different frequencies and apply them to the phase modulators of different axes of the silicon photonic gyroscope, as well as to collect the detector output signals of each axis of the silicon photonic gyroscope and demodulate the rotation speed of the corresponding axis; the constant temperature and constant current control module is used to control the constant temperature and constant current operation of the light source so that the light power of the light source is stably output; the communication interface is used to communicate with the host computer.

[0061] Preferably, the difference frequency modulation and demodulation module also calculates the closed-loop feedback signal caused by each axial rotation speed, and superimposes it on each axial square wave modulation signal to perform closed-loop feedback control.

[0062] In some embodiments, the difference frequency modulation and demodulation module is as follows Figure 3 As shown, it mainly includes X-axis, Y-axis and Z-axis signal generators and X-axis, Y-axis and Z-axis phase-sensitive detectors.

[0063] The X-axis, Y-axis and Z-axis signal generators are used to generate the square wave modulation signals of the X-axis, Y-axis and Z-axis and the closed-loop feedback signals caused by the rotation speed. Among them, the square wave modulation signal frequency f of each axis i is: c / 2nL i , i=X,Y,Z,L i It is the length of the optical fiber loop along the X-axis, Y-axis or Z-axis, c is the speed of light in a vacuum, and n is the refractive index of the optical fiber. Depending on the accuracy, the loop length is usually between 100 and 1000 meters. For this reason, the frequency of the square wave modulation signal is usually between 10 MHz and 100 MHz. According to the different half-wave voltages of the Y waveguide (the half-wave voltage of the Y waveguide is given in the manual), the modulation signal amplitude is set to the half-wave voltage V of the three Y waveguides. pp_i .

[0064] In order to improve the dynamic response capability of the silicon photonic gyroscope, the present invention involves a closed-loop feedback signal according to each axial rotation speed. The closed-loop feedback signal caused by each axial rotation speed is a step wave, such as Figure 4 As shown, the step width T of the step wave step_i is equal to the transit time of the loop, that is

[0065] T step_i =nL i / c

[0066] Where i = X, Y, Z, T step_i It is expressed as the step width of the closed-loop feedback signal caused by the i-axis speed, L i It is expressed as the length of the fiber loop on the i-axis, c is the speed of light in a vacuum, and n is the refractive index of the fiber.

[0067] The step height H of the step wave step_i The peak-to-peak value of the step wave V pp_i And the speed demodulation output D out_i (t) satisfies formula (1):

[0068] H step_i (t) = K tp_i V pp_i D out_i (t) / 2 N (1)

[0069] Among them, Hstep_i (t) is the height of the step wave of the closed-loop feedback signal caused by the rotation speed of the i-axis at time t; N is the number of bits of the DAC (digital-to-analog converter) that generates the step wave, and the number of bits of the DACs of the three axes is the same; K tp_i is the modulation coefficient of the i-axis phase modulator, which is defined as the phase change corresponding to a unit voltage change and is given in the parameter manual of the phase modulator. In this embodiment, the phase modulator is a Y waveguide, and its modulation coefficient can be found in the manual; D out_i (t) is the speed of the demodulated output of axis i at time t; V pp_i is the half-wave voltage of the i-axis phase modulator. Therefore, according to formula (1), the step height can be quickly obtained according to the speed demodulation output. Under a certain transition time, the higher the step wave height, the faster the step wave rises, making the closed loop faster and the gyro can respond quickly to dynamic changes.

[0070] X-axis, Y-axis and Z-axis phase-sensitive detectors are used for X-axis, Y-axis and Z-axis phase deviation detection. The inputs include frequencies f X 、f Y 、f Z The square wave modulation signal and the X-axis, Y-axis and Z-axis detector signal inputs are used. Through correlation detection, the X-axis, Y-axis and Z-axis phase deviations are obtained, that is, the rotation speeds of the three axes of the gyroscope. The phase deviations are not only input into the three signal generators and loaded into the modulation signals of the three axes, but also used as the rotation output of the three axes. Since the phase-sensitive detector works at different detection frequencies, the channel crosstalk signals of different frequencies are completely suppressed in this process.

[0071] As another embodiment of the present invention, taking the above three-axis silicon photonic gyroscope as an example, a method for suppressing crosstalk between axes of a multi-axis silicon photonic gyroscope is provided, comprising the following steps:

[0072] S1: The silicon photonic gyroscope circuit is powered on, and the constant temperature and constant current control module realizes the constant temperature and constant current control of the light source part on the silicon photonic chip to build a stable three-axis silicon photonic gyroscope optical signal transmission and reception;

[0073] S2: The output frequencies of the difference frequency modulation and demodulation modules are f X 、f Y 、f Z , the amplitudes are V pp_X 、V pp_Y 、V pp_Z The square wave modulation signal acts on the X-axis, Y-axis, and Z-axis phase modulators respectively to perform difference frequency modulation on the optical signal;

[0074] S3: The phase-sensitive detectors of the difference frequency modulation and demodulation module are respectively X 、f Y 、f ZThe square wave modulation signal is used to perform digital correlation detection on the detector output signals of the X-axis, Y-axis and Z-axis, and the rotation speed of the X-axis, Y-axis and Z-axis is demodulated. In this process, due to the use of different modulation and demodulation frequencies, the channel crosstalk signal is suppressed;

[0075] S4: The closed-loop feedback signal generates a step wave, the step height and peak-to-peak value of the step wave satisfy formula (1), and is superimposed with the square wave modulation signal, and is loaded onto the phase modulator of each axis through the X-axis, Y-axis and Z-axis modulation signal ports to realize their respective speed closed loops;

[0076] S5: According to the demodulation result of the phase-sensitive detector, it is output as the X-axis, Y-axis and Z-axis gyro output.

[0077] In other embodiments, the silicon photonic gyroscope can be integrated with a two-axis optical channel, and the devices integrated on the silicon photonic chip can also be increased or decreased according to actual conditions. For example, an integrated ring structure can be added to the two-axis silicon photonic chip, or light sources, phase modulators and other devices can be prepared separately and not integrated on the chip. The method provided by the present invention can still be used to achieve crosstalk suppression between multi-axis channels.

[0078] In other implementations, in order to obtain the maximum noise suppression effect, different multi-axis silicon photonic gyroscopes are optimized and designed, and an optimized value scheme of the modulation frequency is designed to obtain a better crosstalk suppression effect:

[0079] (1) For a dual-axis silicon photonic gyroscope, the modulation frequencies of the X-axis and the Y-axis are f i They are designed as: f0, 2f0, and the corresponding lengths of the X-axis and Y-axis optical fiber loops are designed as: c / 2nf0, c / 4nf0, respectively; f0 represents the reference frequency;

[0080] (2) For a three-axis silicon photonic gyroscope, the modulation frequencies f of the X-axis, Y-axis, and Z-axis are i They are designed as: 9f0 / 10, 2f0 and 11f0 / 10 respectively, and the corresponding lengths of the X-axis, Y-axis and Z-axis rings are designed as: 5c / 9nf0, c / 4nf0 and 5c / 11nf0 respectively;

[0081] (3) For the i (i ≥ 4) axis silicon photonic gyroscope, the modulation frequencies of the axes arranged in sequence are set in a cycle according to the rule of 9f0 / 10, 2f0, 11f0 / 10, 2f0. Correspondingly, the loop length is designed to be: c / 2nf i .

[0082] The main reason for adopting the above frequency setting scheme is that the main crosstalk source is the spatial radiation introduced by the silicon photonic chip at a too small distance, so the crosstalk between adjacent channels has a greater impact, that is, the crosstalk between the X-axis and the Y-axis, and the Y-axis and the Z-axis is more significant. Figure 1 As can be seen in (d), when the frequency deviation of adjacent paths is 2D f When the X-axis and Z-axis crosstalk are relatively weak, a better crosstalk suppression effect can be achieved in the above design.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] Parts of the present invention that are not described in detail are well known to those skilled in the art.

Claims

1. A method for suppressing channel crosstalk of a silicon photonic gyroscope based on difference frequency modulation and demodulation, wherein the silicon photonic gyroscope comprises at least two axes, each axis corresponds to a channel, and the silicon photonic gyroscope chip has at least one detector for each channel integrated thereon, characterized in that: The silicon photonic gyroscope channel crosstalk suppression method comprises the following steps: Designing square wave modulation signals of each axial phase modulator, if the silicon photonic gyroscope is not larger than three axes, the frequencies of the square wave modulation signals of each axis are different; if the silicon photonic gyroscope is larger than three axes, the frequencies of the square wave modulation signals of at least two adjacent axes are different; According to the frequency of the square wave modulation signal of each axial phase modulator, the length of the corresponding axial optical fiber loop is set; Adjust the silicon photonic gyroscope light source to operate at constant temperature and constant current; Applying a corresponding square wave modulation signal to the phase modulator of each axis; For the output signal of each axial detector, the square wave modulation signal of the corresponding axial direction is used for digital correlation detection, and the rotation speed of each axial direction is demodulated; The frequency design method of the square wave modulation signal is as follows: The silicon photonic gyroscope has two axes, and the modulation frequencies of the two axes are designed to be: f0, 2f0 respectively, and the lengths of the optical fiber loops of the two axes are correspondingly designed to be: c / 2nf0, c / 4nf0, where f0 represents the reference frequency, c is the speed of light in vacuum, and n is the refractive index of the optical fiber; The silicon photonic gyroscope has three axes, which are arranged in the order of X-axis, Y-axis and Z-axis. The modulation frequencies of the X-axis, Y-axis and Z-axis are designed to be 9f0 / 10, 2f0 and 11f0 / 10 respectively. The lengths of the optical fiber loops of the X-axis, Y-axis and Z-axis are designed to be 5c / 9nf0, c / 4nf0 and 5c / 11nf0 respectively, wherein f0 represents the reference frequency, c is the speed of light in a vacuum, and n is the refractive index of the optical fiber. The silicon photonic gyroscope includes more than four axes, and the modulation frequencies of the axes arranged in sequence are cyclically arranged according to the rules of 9f0 / 10, 2f0, 11f0 / 10, and 2f0; the length of each axial optical fiber loop is: L i =c / 2nf i Where i represents a certain axis of the silicon photonic gyroscope, and f i represents the frequency of the square wave modulation signal on the i-axis, f0 represents the reference frequency, c is the speed of light in a vacuum, and n is the refractive index of the optical fiber.

2. The method for suppressing channel crosstalk of a silicon photonic gyroscope according to claim 1, characterized in that: The amplitude of the square wave modulation signal is the half-wave voltage of its corresponding axial phase modulator.

3. The method for suppressing channel crosstalk of a silicon photonic gyroscope according to claim 1, characterized in that: The silicon photonic gyroscope channel crosstalk suppression method further comprises the following steps: The closed-loop feedback signal caused by the rotational speed of each axis is calculated and superimposed on the square wave modulation signal of each axis to perform closed-loop feedback control.

4. The method for suppressing channel crosstalk of a silicon photonic gyroscope according to claim 3, characterized in that: The closed-loop feedback signal is a step wave, and the step width of the step wave is: T step_i =nL i / c Among them, T step_i It is represented by the step width of the step wave of the closed-loop feedback signal caused by the i-axis speed, i represents a certain axis of the silicon photonic gyroscope, L i It is expressed as the length of the fiber loop on the i-axis, c is the speed of light in a vacuum, and n is the refractive index of the fiber; The step height of the step wave is: H step_i (t)=K tp_i V pp_i D out_i (t) / 2 N Among them, H step_i (t) is the step height of the step wave of the closed-loop feedback signal caused by the i-axis speed at time t; N is the number of bits of the DAC generating the step wave; K tp_i is the modulation coefficient of the i-axis phase modulator; D out_i (t) is the speed of the demodulated output of axis i at time t; V pp_i is the half-wave voltage of the i-axis phase modulator.

5. A silicon photonic gyroscope channel crosstalk suppression device based on difference frequency modulation and demodulation, characterized in that: A silicon photonic gyroscope channel crosstalk suppression method as described in any one of claims 1 to 4 is adopted, wherein the silicon photonic gyroscope channel crosstalk suppression device includes a gyroscope signal detection and crosstalk suppression circuit, and the gyroscope signal detection and crosstalk suppression circuit includes a difference frequency modulation and demodulation module, a constant temperature and constant current control module, and a communication interface. The difference frequency modulation and demodulation module is used to generate square wave modulation signals of different frequencies and apply them to phase modulators of different axes of the silicon photonic gyroscope, and to collect the output signals of the detectors of each axis of the silicon photonic gyroscope, and demodulate the rotation speed of the corresponding axis; the constant temperature and constant current control module is used to control the constant temperature and constant current operation of the light source of the silicon photonic gyroscope, so that the light power of the light source is stably output; and the communication interface is used to communicate with a host computer.

6. The silicon photonic gyroscope channel crosstalk suppression device according to claim 5, characterized in that: The difference frequency modulation and demodulation module is also used to calculate the closed-loop feedback signal caused by the rotation speed of each axial direction, and superimpose it on the square wave modulation signal of each axial direction to perform closed-loop feedback control.

7. The silicon photonic gyroscope channel crosstalk suppression device according to claim 6, characterized in that: The difference frequency modulation and demodulation module includes a group of signal generators and phase-sensitive detectors corresponding to each axis. The signal generator is used to generate a square wave modulation signal of the corresponding axis and a closed-loop feedback signal caused by the rotation speed. The phase-sensitive detector is used to detect the phase deviation of the corresponding axis and output the rotation speed information.

Images