A dual fiber optic ring gyroscope with magnetic field suppression function

Abstract

The present invention discloses a dual-fiber ring gyroscope with a magnetic field suppression function, comprising a light source module, a polarizer, a fiber coupler, first and second circulators, first and second photodetectors, first and second MIOCs, and a PMF ring. Light emitted by the light source module is converted into linearly polarized light by the polarizer and then split into two paths by the fiber coupler. One path passes through the first circulator and enters the first MIOC, where it is further split into two paths, each entering the fiber ring through ports ① and ③ of the PMF ring. At port ①, the first MIOC is docked with the polarization-maintaining fiber at a 0° angle in the fast axis direction, and at port ③, they are rotated 90° and docked. Light from the first MIOC passes through the first circulator and enters the first photodetector for collection. The other light path is similar to the above. A signal processing unit processes the light collected from the two photodetectors to obtain an angular velocity signal. The present invention uses two polarization-maintaining fibers to form a fiber ring, achieving mutual suppression of the magneto-optical Faraday effect.

Description

Technical Field

[0001] The invention belongs to the field of angular acceleration measurement, and in particular relates to a dual-fiber ring gyroscope with a magnetic field suppression function. Background Art

[0002] A fiber optic gyroscope (FOG) is a highly sensitive angular velocity sensor based on a fiber-optic Sagnac interferometer. It has many advantages, including no mechanical components, a wide dynamic range, strong environmental adaptability, and scalable production. It has been widely used in aerospace, weapon navigation, earthquake monitoring, and many other fields.

[0003] Fiber-optic gyros (FOGs) use fiber-optic Sagnac interferometers for angular velocity sensing. To achieve high sensitivity, they often use a particularly long optical fiber wound into a loop to enhance the Sagnac effect. Magnetic field fluctuations induce a magneto-optical Faraday effect on light transmitted through the fiber, causing the polarization plane of the light within the fiber to deflect. This introduces additional noise during fiber-optic sensing. Conventional FOGs typically employ a four-stage symmetrical winding, which effectively suppresses temperature drift caused by the Shupe effect. However, this structure cannot effectively suppress noise caused by magnetic field fluctuations, resulting in reduced sensitivity. This effect is particularly pronounced in FOGs operating in strong magnetic environments. Therefore, FOGs with magnetic field suppression capabilities have significant application value. Summary of the Invention

[0004] In view of the problems existing in the prior art, the object of the present invention is to provide a dual fiber optic ring gyroscope with a magnetic field suppression function.

[0005] The magneto-optical Faraday effect refers to the phenomenon that when a beam of linearly polarized light passes through an optical fiber along the magnetization direction or the direction of an applied magnetic field, the polarization plane rotates. The rotation angle 0 can be expressed as:

[0006] θ F =V·∫ L Bdz, Formula (1)

[0007] Where V is the Wald constant of the medium, B is the magnetic field strength, and L is the length of the fiber in the magnetic field. The formula shows that the Faraday rotation is proportional to the magnetic field component along the direction of light propagation and is the cumulative angle of rotation along the entire fiber propagation direction. Furthermore, the direction of the Faraday rotation is also related to the direction of light propagation. The rule is that if light passes through the fiber once in opposite directions, the total Faraday rotation is zero.

[0008] Based on the above principles, the present invention uses two polarization-maintaining optical fibers wound in a predetermined manner to create a four-port polarization-maintaining fiber ring. Rotary fusion of the fibers achieves mutual suppression of the magneto-optical Faraday effect, thereby producing a dual-fiber ring gyroscope with magnetic field suppression. This invention will provide a theoretical basis and technical support for the development of novel fiber-optic gyros that are insensitive to magnetic fields, promoting their application in space and in environments with strong magnetic interference.

[0009] The technical solution of the present invention is:

[0010] A dual-fiber ring gyroscope with a magnetic field suppression function, characterized by comprising a light source module 1, a polarizer 2, a fiber coupler 3, a first circulator 4 and a second circulator 8, a first photodetector 5 and a second photodetector 9, a first multifunctional integrated optical waveguide modulator 6 and a second multifunctional integrated optical waveguide modulator 10, and a polarization-maintaining dual-fiber ring 7;

[0011] The polarization-maintaining dual-fiber ring 7 includes two polarization-maintaining optical fibers, the fast axis directions of the left half and the right half of each polarization-maintaining optical fiber being perpendicular to each other. The first polarization-maintaining optical fiber is used to wind the first N turns of the odd-numbered layers and the last N turns of the even-numbered layers of the polarization-maintaining dual-fiber ring 7 using a quadrupole symmetry method. The second polarization-maintaining optical fiber is used to wind the first N turns of the even-numbered layers and the last N turns of the odd-numbered layers of the polarization-maintaining dual-fiber ring 7 using a quadrupole symmetry method, and the winding direction of the first polarization-maintaining optical fiber is opposite to that of the second polarization-maintaining optical fiber. The two ends of the first polarization-maintaining optical fiber are denoted as port ① and port ③, and the two ends of the second polarization-maintaining optical fiber are denoted as port ② and port ④.

[0012] The output end of the light source module 1 is connected to the optical fiber coupler 3 via the polarizer 2;

[0013] The optical fiber coupler 3 is used to split the linearly polarized light input after being polarized by the polarizer 2 into two output paths; the first path is input to the beam combining end of the first multifunctional integrated optical waveguide modulator 6 through the first circulator 4, the fast axis direction of the first beam splitting end of the first multifunctional integrated optical waveguide modulator 6 is aligned with the fast axis direction of port ① of the polarization-maintaining dual-fiber ring 7 at 0°, and the fast axis direction of the second beam splitting end of the first multifunctional integrated optical waveguide modulator 6 is aligned with the fast axis direction of port ③ of the polarization-maintaining dual-fiber ring 7 at 90°; the second path is input to the beam combining end of the second multifunctional integrated optical waveguide modulator 10 through the second circulator 8, the fast axis direction of the first beam splitting end of the second multifunctional integrated optical waveguide modulator 10 is aligned with the fast axis direction of port ② of the polarization-maintaining dual-fiber ring 7 at 0°, and the fast axis direction of the second beam splitting end of the second multifunctional integrated optical waveguide modulator 10 is aligned with the fast axis direction of port ④ of the polarization-maintaining dual-fiber ring 12 at 90°;

[0014] The first photodetector 5 is connected to the first circulator 4 and is used to receive the interference light signal returned by the first multifunctional integrated optical waveguide modulator 6;

[0015] The second photodetector 9 is connected to the second circulator 8 and is used to receive the interference light signal returned by the second multifunctional integrated optical waveguide modulator 10 .

[0016] Furthermore, the method for manufacturing the polarization-maintaining dual-fiber ring 7 is as follows: first, the first polarization-maintaining optical fiber is wound clockwise for a first layer using the left half at a 90° reverse connection point perpendicular to the middle fast axis direction, and the second polarization-maintaining optical fiber is wound counterclockwise for a second layer using the left half at a 90° reverse connection point perpendicular to the middle fast axis direction. When the second polarization-maintaining optical fiber is wound at the Nth turn, the two optical fibers are wound at the same time, and the winding is continued for N turns to complete the first two layers; then, the right half of the first polarization-maintaining optical fiber is wound counterclockwise for a third layer, and the right half of the second polarization-maintaining optical fiber is wound clockwise for a fourth layer. When the second polarization-maintaining optical fiber is wound at the same time, the two optical fibers are wound at the same time, and the winding is continued for N turns to complete the third and fourth layers; and the above winding method is repeated to obtain the polarization-maintaining dual-fiber ring 7.

[0017] Furthermore, the polarization-maintaining dual-fiber ring 7 includes 64 layers, N=40, and each layer is wound 80 times.

[0018] Furthermore, the optical path systems of the dual-fiber ring gyroscope all use polarization-maintaining optical fibers.

[0019] Furthermore, the first photodetector 5 and the second photodetector 9 are respectively connected to a signal processing unit, and the signal processing unit is used to perform signal processing on the input detection signal to obtain an angular velocity signal.

[0020] The advantages of the present invention are as follows:

[0021] The present invention offsets the influence of the external magnetic field by rotating and fusing two optical fiber rings and winding them together, and has the advantages of being insensitive to magnetic field changes, temperature changes, high sensitivity, and a wide dynamic range. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the optical path diagram of the dual-fiber ring gyroscope with magnetic field suppression function of the present invention.

[0023] Figure 2 Mapping a dual-fiber surround for sensing.

[0024] Figure numerals: 1. light source module, 2. polarizer, 3. fiber coupler, 4. first circulator, 5. first photodetector, 6. first multifunctional integrated optical waveguide modulator (MIOC), 7. polarization-maintaining dual fiber ring (PMF), 8. second circulator, 9. second photodetector, 10. second multifunctional integrated optical waveguide modulator; 11. polarization-maintaining fiber, 12. fiber core. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] The present invention relates to a dual fiber ring gyroscope with magnetic field suppression function, the optical path diagram of which is as follows: Figure 1As shown. The sensing system of the invention includes a light source module 1, a polarizer 2, a fiber coupler 3, a first circulator 4 and a second circulator 8, a first photodetector 5 and a second photodetector 9, a first multifunctional integrated optical waveguide modulator (MIOC) 6 and a second multifunctional integrated optical waveguide modulator 10, and a polarization-maintaining dual fiber ring (PMF) 7. The entire optical path system adopts a polarization-maintaining fiber design, and the specific working principle is as follows: the light emitted by the light source module 1 becomes linearly polarized light after passing through the polarizer 2, and then is divided into two paths after passing through the fiber coupler 3 and enters the first circulator 4 and the second circulator 8 respectively. The circulator has a directional control for the transmitted light, and at this time it will enter the first MIOC 6 and the second MIOC 10, but will not enter the photodetector. The light entering the first MIOC 6 will be modulated and divided into two paths again, entering the fiber ring through the ① port and ③ port of the PMF ring 7 respectively. At port ①, the fast axis of the first MIOC6 is aligned with the fast axis of the polarization-maintaining fiber at a 0° angle to ensure unchanged polarization state. At port ③, the polarization-maintaining fiber is rotated 90°, aligning the fast axis of the first MIOC6 with the fast axis of the polarization-maintaining fiber at a 90° angle. The light then enters the polarization-maintaining fiber ring, undergoes another 90° alignment in the middle of the ring, and after a complete loop, enters the first MIOC6 again to generate interference. The light exiting the first MIOC6 passes through the first circulator 4 and enters the first photodetector 5 for collection. The other optical path is similar: the light entering the second MIOC10 is also split into two paths, entering the fiber ring through ports ② and ④ of the PMF ring 7, respectively. At port ②, the fast axis of the second MIOC10 is aligned with the fast axis of the polarization-maintaining fiber at a 0° angle. At port ④, the polarization-maintaining fiber is rotated 90°, aligning the fast axis of the second MIOC10 with the fast axis of the polarization-maintaining fiber at a 90° angle. The light then enters the polarization-maintaining fiber loop, undergoes another 90-degree alignment in the middle of the loop, and after completing a full circle, enters the second MIOC 10 again to generate interference. The light exiting the second MIOC 10 passes through the second circulator 8 and enters the second photodetector 9 for collection. The first and second photodetectors 5, 9 are each connected to a signal processing unit. The signal processing unit processes the light collected from the first and second photodetectors 5, 9 to restore the original angular velocity signal.

[0027] Due to the switching of the optical fiber and the synthesis of the dual-loop acquisition signals, the magneto-optical rotation applied to the optical fiber by the change of the external magnetic field will cancel each other out. Therefore, no matter how the external magnetic field changes, the sensitivity of the angular velocity measurement in the present invention will not be significantly reduced.

[0028] In the present invention, the polarization-maintaining dual optical fiber ring 7 for sensing is wound as shown in FIG. Figure 2As shown. The optical fiber core 12 in the figure is used to distinguish the two polarization-maintaining optical fibers and the winding direction. The white core represents the first optical fiber, and the gray core represents the second optical fiber. If the core is empty, it means clockwise winding, and the core with a cross means counterclockwise winding. The specific winding scheme is: the two polarization-maintaining optical fibers 11 are first wound at the middle 90° reverse connection point. The left half of the first polarization-maintaining optical fiber is wound 40 times clockwise in the first layer, and then the left half of the other polarization-maintaining optical fiber is wound 40 times counterclockwise in the second layer. Then, the two polarization-maintaining optical fibers are exchanged in the number of layers and continued to be wound 40 times in the original direction to produce the first two layers. The right halves of the two polarization-maintaining optical fibers are used to be wound 40 times in the opposite direction of the original, and then the number of layers is exchanged and wound again for 40 times to complete the winding of the third and fourth layers. The process is then repeated to alternately wind the two polarization-maintaining optical fibers in a cycle of four layers, for a total of 64 layers, to complete the production of the polarization-maintaining dual optical fiber ring 7.

[0029] While specific embodiments of the present invention have been disclosed for illustrative purposes, intended to facilitate understanding and implementation of the present invention, those skilled in the art will appreciate that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the disclosure of the preferred embodiments, and the scope of protection claimed in the present invention shall be determined by the scope of the claims.

Claims

1. A dual fiber ring gyroscope with magnetic field suppression function, characterized in that: The invention comprises a light source module (1), a polarizer (2), an optical fiber coupler (3), a first circulator (4) and a second circulator (8), a first photodetector (5) and a second photodetector (9), a first multifunctional integrated optical waveguide modulator (6) and a second multifunctional integrated optical waveguide modulator (10), and a polarization-maintaining dual optical fiber ring (7); The polarization-maintaining dual-fiber ring (7) comprises two polarization-maintaining optical fibers, the fast axis directions of the left half and the right half of each polarization-maintaining optical fiber are perpendicular, the first polarization-maintaining optical fiber is used to wind the odd-numbered layers and the last N turns of the even-numbered layers of the polarization-maintaining dual-fiber ring (7) using a quadrupole symmetry method, and the second polarization-maintaining optical fiber is used to wind the even-numbered layers and the first N turns of the odd-numbered layers of the polarization-maintaining dual-fiber ring (7) using a quadrupole symmetry method, and the winding direction of the first polarization-maintaining optical fiber is opposite to the winding direction of the second polarization-maintaining optical fiber; the two ends of the first polarization-maintaining optical fiber are recorded as port ① and port ③, and the two ends of the second polarization-maintaining optical fiber are recorded as port ② and port ④; The output end of the light source module (1) is connected to the optical fiber coupler (3) via the polarizer (2); The optical fiber coupler (3) is used to split the linearly polarized light input after being polarized by the polarizer (2) into two output paths; the first path is input into the beam combining end of the first multifunctional integrated optical waveguide modulator (6) through the first circulator (4); the fast axis direction of the first beam splitting end of the first multifunctional integrated optical waveguide modulator (6) is connected to the fast axis direction of the port ① of the polarization-maintaining dual optical fiber ring (7) at 0°; the fast axis direction of the second beam splitting end of the first multifunctional integrated optical waveguide modulator (6) is connected to the fast axis direction of the port ① of the polarization-maintaining dual optical fiber ring (7) at 0°; The fast axis direction of the port ③ of the polarization-maintaining dual-fiber ring (7) is connected at 90°; the second path is input into the beam combining end of the second multifunctional integrated optical waveguide modulator (10) through the second circulator (8), the fast axis direction of the first beam splitting end of the second multifunctional integrated optical waveguide modulator (10) is connected at 0° to the fast axis direction of the port ② of the polarization-maintaining dual-fiber ring (7), and the fast axis direction of the second beam splitting end of the second multifunctional integrated optical waveguide modulator (10) is connected at 90° to the fast axis direction of the port ④ of the polarization-maintaining dual-fiber ring (7); The first photodetector (5) is connected to the first circulator (4) and is used to receive the interference light signal returned by the first multifunctional integrated optical waveguide modulator (6); The second photodetector (9) is connected to the second circulator (8) and is used to receive the interference light signal returned by the second multifunctional integrated optical waveguide modulator (10).

2. The dual fiber ring gyroscope according to claim 1, wherein: The method for making the polarization-maintaining dual-fiber ring (7) is as follows: first, the left half of the first polarization-maintaining optical fiber is wound clockwise at a 90° reverse connection point perpendicular to the middle fast axis direction to form a first layer, and the left half of the second polarization-maintaining optical fiber is wound counterclockwise at a 90° reverse connection point perpendicular to the middle fast axis direction to form a second layer, and when the Nth turn is reached, the two optical fibers are wound in reverse order for N turns, and the first two layers are wound; then, the right half of the first polarization-maintaining optical fiber is wound counterclockwise for a third layer, and the right half of the second polarization-maintaining optical fiber is wound clockwise for a fourth layer, and when the Nth turn is reached, the two optical fibers are wound in reverse order for N turns, and the third and fourth layers are wound; and the above winding method is repeated to obtain the polarization-maintaining dual-fiber ring (7).

3. The dual fiber ring gyroscope according to claim 2, wherein: The polarization-maintaining dual optical fiber ring (7) comprises 64 layers, N=40, and each layer is wound 80 times.

4. The dual fiber ring gyroscope according to claim 1, 2 or 3, characterized in that: The optical path systems of the dual-fiber ring gyroscope all use polarization-maintaining optical fibers.

5. The dual fiber ring gyroscope according to claim 1, 2 or 3, characterized in that: The first photodetector (5) and the second photodetector (9) are respectively connected to a signal processing unit, and the signal processing unit is used to perform signal processing on the input detection signal to obtain an angular velocity signal.

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