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

Abstract

The application discloses a kind of time division multiplexing three-axis wide spectrum light source resonant type fiber-optic gyroscope detection systems and methods, belong to gyroscope optical system design field.System is constituted by optical system and signal detection system, and optical system includes a wide spectrum light source, a push-pull Y waveguide, a circulator, three mutually orthogonal transmission type fiber ring resonant cavity, two sections of delay optical fiber and a photoelectric detector;Signal detection system includes modulation and demodulation module, time division decoupling module and low-pass filter module.Three transmission type fiber ring resonant cavities are sequentially connected, and the time of optical signal reaching three fiber ring resonant cavities is different by being set delay optical fiber between adjacent two transmission type fiber ring resonant cavities.The application ingeniously designs three fiber ring resonant cavities to form three-axis integrated structure.In this way, the time difference of three-axis signals is utilized, and multiplexing in time domain can be realized without adding additional devices.

Description

Technical Field

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

[0002] A fiber-optic gyroscope (FOG) is a high-precision angular velocity sensing element based on the optical Sagnac effect, widely used in inertial navigation. It mainly includes two types: interferometric fiber-optic gyroscopes (IFOGs) and resonator fiber-optic gyroscopes (RFOGs). IFOGs use fiber loops as sensing elements, detecting angular velocity through changes in interference light intensity; their theoretical sensitivity is proportional to the fiber length. RFOGs use fiber resonant cavities as sensing elements, utilizing multi-turn propagation of light within the cavity to enhance the Sagnac effect; their theoretical sensitivity is proportional to the product of fiber length and resonant cavity sharpness. For the same length, RFOGs have higher theoretical sensitivity. Replacing the narrow-linewidth laser in traditional classical RFOGs with a broadband light source helps reduce the impact of optical noise related to light source coherence, such as backscattering, polarization fluctuations, and the optical Kerr effect, on the gyroscope's detection accuracy. However, when driven by a broadband light source, the fiber optic resonator is used as a filter. At this time, most of the power of the broadband light source is not fully utilized for the detection of the gyroscope angular velocity signal, resulting in a waste of light source power. Therefore, in a broadband light source driven RFOG, it is of great significance to study how to improve power utilization.

[0003] Furthermore, in practical gyroscope applications, it is often necessary to simultaneously detect angular velocities in three mutually orthogonal directions. To reduce the cost and size of three-axis fiber optic gyroscopes, a common approach is to use three fiber optic rings or fiber optic resonators sharing a single light source. However, other optical path components besides the light source, including Y-waveguide modulators, fiber optic couplers or circulators, and photodetectors, typically require three separate sets. This invention proposes using time-division multiplexing technology to achieve three fiber optic resonators sharing a single gyroscope optical path, potentially resulting in a simpler and lower-cost three-axis gyroscope. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a time-division multiplexed three-axis broadband light source resonant fiber optic gyroscope detection system and method.

[0005] This invention is achieved through the following technical solution:

[0006] In a first aspect, the present invention discloses a time-division multiplexed three-axis broadband light source resonant fiber optic gyroscope detection system, including an optical system and a signal detection system. The optical system includes a broadband light source, a push-pull Y waveguide, a circulator, three mutually orthogonal fiber optic ring resonant cavities, two delay fibers, and a photodetector. The signal detection system consists of a modulation and demodulation module, a time decoupling module, and a low-pass filter module.

[0007] A broadband light source, a circulator, and a push-pull Y-waveguide are connected in sequence. The two output ports of the push-pull Y-waveguide are connected to two ports on one side of the first fiber optic ring resonator. The three fiber optic ring resonators are connected in sequence. The two ports on one side of each fiber optic ring resonator are connected to the two ports on one side of another fiber optic ring resonator through a connection link. A delay fiber is provided on one of the connection links between the two fiber optic ring resonators. The circulator is also connected to a photodetector.

[0008] The photodetector is connected to the modulation and demodulation module. The modulation and demodulation module generates a modulation signal and outputs it to the time decoupling module. It also 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 the 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 fiber ring resonators and outputs it to the external data logger.

[0009] Secondly, the present invention discloses a time-division multiplexed three-axis broadband light source resonant fiber optic gyroscope detection method, comprising the following steps:

[0010] The broadband light source outputs broadband light that passes through a circulator and a push-pull Y-waveguide in sequence and then enters three mutually orthogonal fiber ring resonators. The three fiber ring resonators return light with three 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 timing processing on the modulation signal and loads the processing result onto the push-pull Y-waveguide. The push-pull Y-waveguide modulates the phase of 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 filter module for low-pass filtering. The time decoupling module receives the demodulated signal output from the low-pass filter module, performs timing decoupling on it, obtains the angular velocity information of the three fiber ring resonators, and outputs it to an external data logger.

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

[0013] This invention achieves triaxial detection by simply adding two resonant cavities to a single-axis gyroscope system, without requiring additional components, which is extremely advantageous for miniaturization.

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

[0015] This invention uses time-division multiplexing to distinguish the three-axis signals in the time domain, thus ensuring that the three-axis gyroscope operates independently in the time domain.

[0016] This invention utilizes a broadband light source to effectively reduce optical parasitic effects in the system, thereby greatly improving the system's stability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a time-division multiplexed three-axis broadband light source resonant fiber optic gyroscope detection system.

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

[0019] In the diagram: 1. Broadband light source; 2. Circulator; 3. Push-pull Y-waveguide; 4. Photodetector; 5. First delay fiber; 6. Second delay 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 logger. Detailed Implementation

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

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

[0022] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

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

[0026] A broadband light source, a circulator, a push-pull Y-waveguide, and a first fiber optic 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 of the push-pull Y-waveguide, the third port of the circulator is connected to the input of the photodetector, and the two output ports of the push-pull Y-waveguide are connected to two ports on one side of the first fiber optic ring resonator.

[0027] Two ports on the other side of the first fiber optic ring resonator are each connected to two ports on one side of the second fiber optic ring resonator via a connection link. A first delay fiber is provided on one of the connection links between the first and second fiber optic ring resonators. Specifically, one port on the other side of the first fiber optic ring resonator is connected to one end of the first delay fiber, and the other end of the first delay fiber is connected to one port on one side of the second fiber optic ring resonator. The other port on the other side of the first fiber optic ring resonator is directly connected to the other port on one side of the second fiber optic ring resonator.

[0028] Two ports on the other side of the second fiber optic ring resonator are each connected to two ports on one side of the third fiber optic ring resonator via a connecting link. A second delay fiber is installed on one of the connecting links between the second and third fiber optic ring resonators. Specifically, one port on the other side of the second fiber optic ring resonator is connected to one end of the second delay fiber, and the other end of the second delay fiber is connected to one port on one side of the third fiber optic ring resonator. The other port on the other side of the second fiber optic ring resonator is directly connected to the other port on one side of the third fiber optic ring resonator. The two ports on the other side of the third fiber optic ring resonator are left unused.

[0029] The output of the photodetector is connected to the modulation and demodulation module. The modulation and demodulation module 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 time-series processing on the modulation signal and loads the processing result onto the push-pull Y-waveguide. The push-pull Y-waveguide modulates the phase of 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 demodulated signal to the time decoupling module. The time decoupling module performs time-series decomposition on the demodulated signal to obtain the angular velocity information of the three fiber ring resonators and outputs it to the external data logger.

[0030] The delay fiber configuration causes the optical signal to arrive at the second and third fiber ring resonators at different times, and also results in different delays in the returned optical signals from the three fiber ring resonators, which can then be distinguished by the photodetector. The three fiber ring resonators have similar cavity lengths, and the recommended length of the two delay fiber segments is one-third of the cavity length of the first fiber ring resonator.

[0031] In one specific embodiment of the present invention, the fiber optic ring resonator is a transmission type fiber optic ring resonator, which filters the input optical signal and has four ports. The transmission type fiber optic 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 one specific embodiment of the present invention, the present invention also provides a detection method for a time-division multiplexed three-axis broadband light source resonant fiber optic gyroscope detection system, the specific detection method being as follows: Figure 2 As shown.

[0033] A broadband light source 1 outputs broadband light to the first port of a circulator 2. The broadband light then passes through the second port of the circulator 2 and is output to a push-pull Y-waveguide 3. The push-pull Y-waveguide 3 splits the broadband light into two paths, which are injected into the first fiber optic ring resonator 7 respectively. Both paths undergo multiple turns of propagation within the cavity. After multiple turns of propagation, the two paths of propagation are output to the push-pull Y-waveguide 3. Simultaneously, one path of propagation passes through the first delay fiber 5 and is then input into the second fiber optic ring resonator 8. The other path of propagation is directly input into the second fiber optic ring resonator 8. The two paths of propagation with different delays received by the second fiber optic ring resonator 8 also undergo multiple turns of propagation within the cavity. After multiple turns of propagation, the two paths of propagation with different delays are output to the push-pull Y-waveguide 3. In waveguide 3, one of the beams after multi-turn transmission in the second fiber ring resonator 8 passes through the second delay fiber 6 and is input into the third fiber ring resonator 9. The other beam is directly input into the third fiber ring resonator 9. The two beams received by the third fiber ring resonator 9 also undergo multi-turn transmission within the cavity. The two beams after multi-turn transmission are output to the push-pull Y-waveguide 3. The push-pull Y-waveguide 3 receives the three beams with different delays and modulates their phases to obtain three optical signals with different delays, which are then output to the circulator 2. The three optical signals are input to the photodetector 4 through the third port of the circulator 2 for photoelectric conversion. The photodetector 4 outputs an electrical signal 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 modulates the phase of 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 the demodulation result and outputs the demodulation result to the low-pass filter module 12. The low-pass filter module 12 performs low-pass filtering on the demodulation result and outputs the demodulated signal to the time decoupling module 11. The time decoupling module 11 decomposes the demodulated signal in time based on the period of the internally generated timing pulse signal and the time delay caused by the delay fiber. Then, it extracts all the signals corresponding to each fiber ring resonator and finally obtains the angular velocity information of the three fiber ring resonators. The angular velocity information of each fiber ring resonator is then output to the external data recorder.

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

[0036] 1) The time decoupling module generates a pulse signal, the period of which is the average 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 modulated 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 multiplication as the processing result.

[0039] This invention enables the driving of a three-gyroscope system using only a broadband light source, a push-pull Y-waveguide, a circulator, and a photodetector, without requiring additional optical components. This greatly simplifies the system structure, effectively improves the utilization rate of the light source, and significantly reduces costs. Furthermore, this invention ensures the signal independence of the three single-axis gyroscopes by utilizing the time difference between the three-axis signals to distinguish them.

[0040] In this invention, light passes through different fiber optic ring resonant cavities and delay fibers, creating a time difference. Therefore, the signals received by the photodetector exhibit a time difference, which is used to distinguish the three-axis signals. Compared to a typical three-axis gyroscope system, the system structure is greatly simplified, reducing overall cost and facilitating the practical application of resonant fiber optic gyroscopes.

[0041] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. Those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for detecting a three-axis broadband light source resonant fiber optic gyroscope using a time-division multiplexing system, characterized in that, The detection system includes an optical system and a signal detection system. The optical system includes a broadband light source, a push-pull Y waveguide, a circulator, three mutually orthogonal fiber ring resonant cavities, two delay fibers, 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 broadband light source, a circulator, and a push-pull Y-waveguide are connected in sequence. The two output ports of the push-pull Y-waveguide are connected to two ports on one side of the first fiber optic ring resonator. The three fiber optic ring resonators are connected in sequence. The two ports on one side of each fiber optic ring resonator are connected to the two ports on one side of another fiber optic ring resonator through a connection link. A delay fiber is provided on one of the connection links between the two fiber optic ring resonators. The circulator is also connected to a photodetector. The photodetector is connected to the modulation and demodulation module. The modulation and demodulation module generates a modulation signal and outputs it to the time decoupling module. It also 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 the 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 fiber ring resonators and outputs it to the external data logger; The setting of the delay fiber makes the time when the optical signal arrives at the second fiber ring resonator and the third fiber ring resonator different, and also makes the optical signals returned by the three fiber ring resonators have different delays, so that they can be distinguished by the photodetector. The three fiber ring resonators have equal cavity lengths, and the lengths of the two delay fiber segments are each one-third of the cavity length of the first fiber ring resonator. The method includes the following steps: The broadband light source outputs broadband light that passes through a circulator and a push-pull Y-waveguide in sequence and then enters three mutually orthogonal fiber ring resonators. The three fiber ring resonators return light with three 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 timing processing on the modulation signal and loads the processing result onto the push-pull Y-waveguide. The push-pull Y-waveguide modulates the phase of 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 filter module for low-pass filtering. The time decoupling module receives the demodulated signal output from the low-pass filter module, performs timing decoupling on it, obtains the angular velocity information of the three fiber ring resonators, and outputs it to the external data logger. The time decoupling module performs timing processing on the modulated signal, specifically including: 1) The time decoupling module generates a pulse signal, the period of which is the average 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 modulated 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 multiplication as the processing result; The time series decomposition includes: The time-decoupling module processes the demodulated signal in chronological order based on the phase delay caused by the internally generated pulse signal and the delay fiber, and then extracts the signals corresponding to each fiber ring resonator to finally obtain the angular velocity information of the three fiber ring resonators.

2. The detection method for a three-axis broadband light source resonant fiber optic gyroscope according to claim 1, characterized in that, The broadband light source is connected to the first port of the circulator, the second port of the circulator is connected to the input of the push-pull Y-waveguide, and the third port of the circulator is connected to the input of the photodetector.

3. The detection method for a three-axis broadband light source resonant fiber optic gyroscope according to claim 1, characterized in that, All three fiber optic ring resonators are transmission-type fiber optic ring resonators, and they adopt a transmission-type symmetrical connection method in which optical signals in both clockwise and counterclockwise directions share the same input and output ports.

4. The detection method for a three-axis broadband light source resonant fiber optic gyroscope according to claim 1, characterized in that, The two ports on the other side of the first fiber ring resonator are each connected to two ports on one side of the second fiber ring resonator via a connection link, and a first delay fiber is provided on one of the connection links between the first and second fiber ring resonators; the two ports on the other side of the second fiber ring resonator are each connected to two ports on one side of the third fiber ring resonator via a connection link, and a second delay fiber is provided on one of the connection links between the second and third fiber ring resonators, while the two ports on the other side of the third fiber ring resonator are left unused.

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