Time division multiplexing three-axis wide-spectrum light source resonant optical fiber gyroscope detection system and method

Abstract

The invention discloses a time division multiplexing three-axis wide-spectrum light source resonant optical fiber gyroscope detection system and method, and belongs to the field of gyroscope light path system design. The system is composed of an optical system and a signal detection system, wherein the optical system comprises a wide-spectrum light source, a push-pull Y waveguide, a circulator, three mutually orthogonal transmission-type optical fiber annular resonant cavities, two sections of delay optical fibers and a photoelectric detector; the signal detection system comprises a modulation-demodulation module, a time-delay decoupling module and a low-pass filtering module. Wherein the three transmission-type optical fiber annular resonant cavities are connected in sequence, and the time delay optical fiber is arranged between every two adjacent transmission-type optical fiber annular resonant cavities, so that the time when an optical signal reaches the three optical fiber annular resonant cavities is different. The three optical fiber annular resonant cavities are ingeniously designed to form a three-axis integrated structure. In this way, the time difference of the three-axis signals is utilized, and multiplexing on the time domain can be achieved without adding extra devices.

Description

Technical Field

[0001] The invention relates to a time-division multiplexed three-axis wide-spectrum light source resonant optical fiber gyroscope detection system and method, belonging to the field of gyroscope optical path system design. Background Art

[0002] Fiber-optic gyroscope (FOG) is a high-precision angular velocity sensitive element based on the optical Sagnac effect and is widely used in the field of inertial navigation. It mainly includes two types: interferometric fiber-optic gyroscope (IFOG) and resonator fiber-optic gyroscope (RFOG). IFOG uses a fiber ring as a sensitive element and detects angular velocity by changing the intensity of interference light. Its theoretical sensitivity is proportional to the length of the fiber. RFOG uses a fiber resonant cavity as a sensitive element and uses multiple turns of light in the resonant cavity to enhance the Sagnac effect. Its theoretical sensitivity is proportional to the product of the fiber length and the clarity of the resonant cavity. At the same length, RFOG has a higher theoretical sensitivity. Using a wide-spectrum light source instead of a narrow-linewidth laser in the traditional classical RFOG is beneficial to reduce the influence of optical noise related to the coherence of the light source, such as backscattering, polarization fluctuation, and optical Kerr effect, on the gyroscope detection accuracy. However, when driven by a wide-spectrum light source, the fiber resonant cavity is used as a filter. At this time, most of the power of the wide-spectrum light source cannot be fully used for the detection of the gyroscope angular velocity signal, resulting in a waste of light source power. Therefore, in the RFOG driven by a wide-spectrum light source, it is of great significance to study how to improve the power utilization.

[0003] In addition, when the gyroscope is actually used, it is often necessary to simultaneously realize sensitive detection of angular velocity in three mutually orthogonal directions. In order to reduce the cost and size of the three-axis fiber optic gyroscope, three fiber rings or fiber resonant cavities are often used to share a light source, while other optical path devices other than the light source, including Y-waveguide modulators, fiber couplers or circulators, and photodetectors, usually require three independent sets. The present invention proposes to use time division technology multiplexing to realize three fiber resonant cavities sharing a gyroscope optical path, which is expected to realize a three-axis gyroscope with a simpler structure and lower cost. Summary of the invention

[0004] The purpose of the present invention is to provide a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system and method in view of the deficiencies in the prior art.

[0005] The present invention is achieved through the following technical solutions:

[0006] In the first aspect, the present invention discloses a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system, comprising an optical system and a signal detection system, wherein the optical system comprises a wide-spectrum light source, a push-pull Y-waveguide, a circulator, three mutually orthogonal fiber ring resonators, two sections of delayed optical fiber and a photodetector, and the signal detection system comprises a modulation and demodulation module, a time decoupling module and a low-pass filtering module;

[0007] A wide-spectrum light source, a circulator and a push-pull Y-waveguide are connected in sequence, and two output ports of the push-pull Y-waveguide are connected to two ports on one side of a first fiber ring resonator; three fiber ring resonators are connected in sequence, and two ports on one side of each fiber ring resonator are respectively connected to two ports on one side of another fiber ring resonator through a connecting link, and a delay optical fiber is arranged on one of the connecting links between the two fiber ring resonators; the circulator is also connected to a photodetector;

[0008] The photodetector is connected to the modulation and demodulation module, which generates a modulation signal and outputs it to the time-decoupling module, demodulates the output of the photodetector, and outputs the demodulation result to the low-pass filtering module; the low-pass filtering module outputs the demodulated signal to the time-decoupling module; the time-decoupling module obtains a processing result based on the modulation signal, and loads the processing result onto the push-pull Y waveguide; the time-decoupling module obtains the angular velocity information of the three optical fiber ring resonators and outputs it to an external data recorder.

[0009] In a second aspect, the present invention discloses a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection method, comprising the following steps:

[0010] The broadband light source outputs broadband light, which passes through the circulator and the push-pull Y-waveguide in sequence and then enters three mutually orthogonal fiber ring resonators. The three fiber ring resonators return three lights with different delays to the push-pull Y-waveguide. The push-pull Y-waveguide outputs three optical signals with different phases to the circulator. The three optical signals pass through the circulator and enter the photodetector. The photodetector outputs the detection result to the modulation and demodulation module.

[0011] The modulation and demodulation module generates a modulation signal and outputs it to the time-decoupling module. The time-decoupling module performs time processing on the modulation signal and loads the processing result onto the push-pull Y-waveguide. The push-pull Y-waveguide performs phase modulation on the light passing through it according to the processing result. At the same time, the modulation and demodulation module demodulates the output of the photodetector and outputs the demodulation result to the low-pass filtering module for low-pass filtering. The time-decoupling module receives the demodulated signal output by the low-pass filtering module, performs time-series decomposition on it, obtains the angular velocity information of the three fiber ring resonators, and outputs it to an external data recorder.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] The present invention can realize three-axis detection by only adding two resonant cavities on the basis of a single-axis gyroscope system without requiring additional components, which is extremely beneficial to miniaturization.

[0014] The present invention greatly improves the utilization rate of the light source by using the resonant cavities in series.

[0015] The present invention distinguishes three-axis signals in the time domain through time division multiplexing, so that the three-axis gyroscope can work independently in the time domain.

[0016] The present invention utilizes a wide-spectrum light source to effectively reduce optical parasitic effects in the system, thereby greatly improving the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system;

[0018] Figure 2 It is a schematic diagram of a specific implementation case of a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system;

[0019] In the figure: 1. Broad-spectrum light source; 2. circulator; 3. push-pull Y-waveguide; 4. photodetector; 5. first section of delay optical fiber; 6. second section of delay optical fiber; 7. first fiber ring resonator; 8. second fiber ring resonator; 9. third fiber ring resonator; 10. modulation and demodulation module; 11. time decoupling module; 12. low-pass filter module; 13. data recorder. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0022] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0025] like Figure 1 As shown, a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system includes an optical system consisting of a wide-spectrum light source, a push-pull Y-waveguide, a circulator, three mutually orthogonal transmission fiber optic ring resonators, two sections of delay fiber, a photodetector, and a signal detection system consisting of a modulation and demodulation module, a time decoupling module, and a low-pass filtering module.

[0026] The broadband light source, the circulator, the push-pull Y-waveguide and the first fiber ring resonator are connected in sequence. Specifically, the broadband light source is connected to the first port of the circulator, the second port of the circulator is connected to the input end of the push-pull Y-waveguide, the third port of the circulator is connected to the input end of the photodetector, and the two output ports of the push-pull Y-waveguide are connected to the two ports on one side of the first fiber ring resonator.

[0027] The two ports on the other side of the first fiber ring resonator are respectively connected to the two ports on one side of the second fiber ring resonator through a connecting link, and a first section of delay optical fiber is arranged on one of the connecting links between the first fiber ring resonator and the second fiber ring resonator; specifically, one port on the other side of the first fiber ring resonator is connected to one end of the first section of delay optical fiber, and the other end of the first section of delay optical fiber is connected to one of the ports on one side of the second fiber ring resonator; the other port on the other side of the first fiber ring resonator is directly connected to the other port on one side of the second fiber ring resonator.

[0028] The two ports on the other side of the second fiber ring resonator are respectively connected to the two ports on one side of the third fiber ring resonator through a connection link, and a second delay optical fiber is provided on one of the connection links between the second fiber ring resonator and the third fiber ring resonator; specifically, one port on the other side of the second fiber ring resonator is connected to one end of the second delay optical fiber, and the other end of the second delay optical fiber is connected to one of the ports on one side of the third fiber ring resonator; another port on the other side of the second fiber ring resonator is directly connected to another port on one side of the third fiber ring resonator. The two ports on the other side of the third fiber ring resonator are vacant.

[0029] The output end of the photodetector is connected to the modulation and demodulation module, which demodulates the output of the photodetector and outputs the demodulation result to the low-pass filter module; the modulation and demodulation module also generates a modulation signal and outputs it to the time-decoupling module, the time-decoupling module performs timing processing on the modulation signal and loads the processing result onto the push-pull Y-waveguide, and the push-pull Y-waveguide performs phase modulation on the light passing through it according to the processing result; the low-pass filter module performs low-pass filtering on the demodulation result and outputs the demodulation signal to the time-decoupling module, the time-decoupling module performs time-series decomposition on the demodulation signal, obtains the angular velocity information of the three fiber ring resonators and outputs it to an external data recorder.

[0030] The setting of the delayed light makes the time for the light signal to reach the second fiber ring resonator and the third fiber ring resonator different, and also makes the light signals returned by the three fiber ring resonators have different delays, so that they can be distinguished by the photoelectric detector. The three fiber ring resonators have similar cavity lengths, and the length of the two delay fibers is recommended to be one third of the length of the first fiber ring resonator.

[0031] In a specific embodiment of the present invention, the fiber ring resonator is a transmission-type fiber ring resonator, which filters the input optical signal and has four ports; the transmission-type fiber ring resonator adopts a transmission-type symmetrical connection method in which the clockwise and counterclockwise optical signals share the input and output ports, which is extremely beneficial to improving the signal-to-noise ratio of the gyroscope output.

[0032] In a specific embodiment of the present invention, the present invention also provides a detection method for a time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system. The specific detection method is as follows: Figure 2 shown.

[0033] The broadband light source 1 outputs broadband light to the first port of the circulator 2, and the broadband light is then output to the push-pull Y waveguide 3 through the second port of the circulator 2. The push-pull Y waveguide 3 divides the broadband light into two paths of light and injects them into the first fiber ring resonator 7 respectively. Both paths of light are transmitted multiple turns in the cavity, and the two paths of light after multiple turns of transmission are output to the push-pull Y waveguide 3. At the same time, one path of light after multiple turns of transmission passes through the first delay optical fiber 5 and is then input into the second fiber ring resonator 8. The other path of light after multiple turns of transmission is directly input into the second fiber ring resonator 8. The two paths of light with different delays received by the second fiber ring resonator 8 are also transmitted multiple turns in the cavity, and the two paths of light with different delays after multiple turns of transmission are output to the push-pull Y waveguide 3. In the push-pull Y waveguide 3, one of the lights after multi-circle transmission in the second fiber ring resonator 8 is input into the third fiber ring resonator 9 after passing through the second delay fiber 6, and the other light is directly input into the third fiber ring resonator 9. The two lights received by the third fiber ring resonator 9 are also multi-circle transmitted in the cavity, and the two lights after multi-circle transmission are output to the push-pull Y waveguide 3; the push-pull Y waveguide 3 receives the three lights with different delays, and phase modulates them to obtain three light signals with different delays and output them to the circulator 2, and the three light signals are input into the photodetector 4 through the third port of the circulator 2 for photoelectric conversion, and the photodetector 4 outputs electrical signals to the modulation and demodulation module 10.

[0034] The modulation and demodulation module 10 generates a modulation signal and outputs it to the time-decoupling module 11. The time-decoupling module 11 performs timing processing on the modulation signal and loads the processing result onto the push-pull Y waveguide 3. The push-pull Y waveguide 3 performs phase modulation on the light passing through it according to the processing result. At the same time, the modulation and demodulation module 10 demodulates the electrical signal output by the photodetector 4 to obtain a demodulation result, and outputs the demodulation result to the low-pass filtering module 12. The low-pass filtering module 12 performs low-pass filtering on the demodulation result and outputs the demodulation signal to the time-decoupling module 11. The time-decoupling module 11 decomposes the demodulated signal in time based on the internally generated timing pulse signal period and the time delay caused by the delay optical fiber, and then extracts all signals corresponding to each fiber ring resonator, and finally obtains the angular velocity information of the three fiber ring resonators, and outputs the angular velocity information of each fiber ring resonator to an external data recorder.

[0035] In a specific embodiment of the present invention, the time decoupling module performs time sequence processing on the modulation signal, specifically including:

[0036] 1) A pulse signal is generated inside the time decoupling module, the period of the pulse signal is the average value of the transit time of the three fiber ring resonators, and the duty cycle is one quarter to one third;

[0037] 2) The time decoupling module receives the modulation signal generated by the modulation and demodulation module;

[0038] 3) The time decoupling module multiplies the received modulation signal with the pulse signal, and uses the new modulation signal obtained by the multiplication as the processing result.

[0039] The present invention can realize the driving of three gyroscope systems by using only one wide-spectrum light source, one push-pull Y waveguide, one circulator and one photodetector, and no additional optical elements are needed, which greatly simplifies the structure of the system, effectively improves the utilization rate of the light source, and effectively reduces the cost. In addition, the present invention distinguishes the signals by using the time difference between the three-axis signals, thereby ensuring the signal independence of the three single-axis gyroscopes.

[0040] In the present invention, light passes through different fiber ring resonators and delay fibers to form a time difference. Therefore, the signal received by the photodetector has a time difference, based on which the three-axis signal is distinguished. Compared with the general three-axis gyroscope system, the system structure is greatly simplified, the overall cost is reduced, and it is conducive to the practical application of the resonant fiber optic gyroscope.

[0041] The above-mentioned embodiments only express several implementation modes of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system, characterized in that: It includes an optical system and a signal detection system. The optical system includes a wide-spectrum light source, a push-pull Y waveguide, a circulator, three mutually orthogonal fiber ring resonators, two sections of delayed optical fiber and a photodetector. The signal detection system consists of a modulation and demodulation module, a time decoupling module and a low-pass filter module. A wide-spectrum light source, a circulator and a push-pull Y-waveguide are connected in sequence, and two output ports of the push-pull Y-waveguide are connected to two ports on one side of a first fiber ring resonator; three fiber ring resonators are connected in sequence, and two ports on one side of each fiber ring resonator are respectively connected to two ports on one side of another fiber ring resonator through a connecting link, and a delay optical fiber is arranged on one of the connecting links between the two fiber ring resonators; the circulator is also connected to a photodetector; The photodetector is connected to the modulation and demodulation module, which generates a modulation signal and outputs it to the time-decoupling module, demodulates the output of the photodetector, and outputs the demodulation result to the low-pass filter module; the low-pass filter module outputs the demodulated signal to the time-decoupling module; The time-decoupling module obtains processing results based on the modulation signal and loads the processing results onto the push-pull Y-waveguide; the time-decoupling module obtains angular velocity information of the three fiber ring resonators and outputs it to an external data recorder.

2. The time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system according to claim 1 is characterized in that: The broadband light source is connected to a first port of the circulator, a second port of the circulator is connected to an input end of a push-pull Y-waveguide, and a third port of the circulator is connected to an input end of a photodetector.

3. The time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system according to claim 1, characterized in that: The three fiber ring resonators are all transmission-type fiber ring resonators, and adopt a transmission-type symmetrical connection method in which the optical signals in the clockwise and counterclockwise directions share the input and output ports.

4. The time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system according to claim 1, characterized in that: The two ports on the other side of the first fiber ring resonator are each connected to the two ports on one side of the second fiber ring resonator through a connection link, and a first section of delay optical fiber is provided on one of the connection links between the first fiber ring resonator and the second fiber ring resonator; the two ports on the other side of the second fiber ring resonator are each connected to the two ports on one side of the third fiber ring resonator through a connection link, and a second section of delay optical fiber is provided on one of the connection links between the second fiber ring resonator and the third fiber ring resonator, and the two ports on the other side of the third fiber ring resonator are vacant.

5. The time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system according to claim 1, characterized in that: The setting of the delay optical fiber makes the optical signal reach the second optical fiber ring resonator and the third optical fiber ring resonator at different times, and also makes the optical signals returned from the three optical fiber ring resonators have different delays, so that they can be distinguished by the photoelectric detector.

6. The time-division multiplexed three-axis wide-spectrum light source resonant fiber optic gyroscope detection system according to claim 5, characterized in that: The three fiber ring resonant cavities have the same length, and the lengths of the two delay optical fibers are each one-third of the length of the first fiber ring resonant cavity.

7. A detection method for a three-axis wide-spectrum light source resonant fiber optic gyroscope based on the detection system of claim 1, characterized in that: The following steps are involved: The broadband light source outputs broadband light, which passes through the circulator and the push-pull Y-waveguide in sequence and then enters three mutually orthogonal fiber ring resonators. The three fiber ring resonators return three lights with different delays to the push-pull Y-waveguide. The push-pull Y-waveguide outputs three optical signals with different phases to the circulator. The three optical signals pass through the circulator and enter the photodetector. The photodetector outputs the detection result to the modulation and demodulation module. The modulation and demodulation module generates a modulation signal and outputs it to the time-decoupling module. The time-decoupling module performs time processing on the modulation signal and loads the processing result onto the push-pull Y-waveguide. The push-pull Y-waveguide performs phase modulation on the light passing through it according to the processing result. At the same time, the modulation and demodulation module demodulates the output of the photodetector and outputs the demodulation result to the low-pass filtering module for low-pass filtering. The time-decoupling module receives the demodulated signal output by the low-pass filtering module, performs time-series decomposition on it, obtains the angular velocity information of the three fiber ring resonators, and outputs it to an external data recorder.

8. The detection method of a three-axis wide-spectrum light source resonant fiber optic gyroscope according to claim 7, characterized in that: The time decoupling module performs timing processing on the modulated signal, including: 1) A pulse signal is generated inside the time decoupling module, the period of the pulse signal is the average value of the transit time of the three fiber ring resonators, and the duty cycle is one quarter to one third; 2) The time decoupling module receives the modulation signal generated by the modulation and demodulation module; 3) The time decoupling module multiplies the received modulation signal with the pulse signal, and uses the new modulation signal obtained by the multiplication as the processing result.

9. The detection method of a three-axis wide-spectrum light source resonant fiber optic gyroscope according to claim 7, characterized in that: The timing decomposition includes: The time decoupling module processes the demodulated signal in time sequence based on the internally generated pulse signal and the phase delay caused by the delay optical fiber, and then extracts the signal corresponding to each fiber ring resonator, and finally obtains the angular velocity information of the three fiber ring resonators.

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