阅读说明：本技术 一种基于多芯光纤实现光纤陀螺灵敏度倍增的装置及方法 (Device and method for realizing sensitivity multiplication of fiber-optic gyroscope based on multi-core fiber ) 是由 缪立军 闫景涛 石锦 黄腾超 车双良 舒晓武 于 2020-12-11 设计创作，主要内容包括：本发明公开了一种基于多芯光纤实现光纤陀螺灵敏度倍增的装置及方法。宽谱光源发出的光通过光耦合器和Y型多功能集成光学器件分成两路,分别沿着顺时针和逆时针方向从两个扇入扇出模块的扇入端进入多芯光纤环中；在光束完全通过当前纤芯后由扇入扇出模块引导至另一根纤芯并以相同的方向传播,如此多次循环直到两束光经过全部纤芯,由扇出端离开多芯光纤环；数字闭环信号处理电路通过采集和处理光探测器的电信号得到载体转速信息并完成反馈和调制。本发明所述光纤陀螺的有效光路长度为光纤环长的数倍,从而使萨格奈克相移和灵敏度达到倍增效果,同时能够降低光纤环绕制工艺难度和成本。本发明也适用于光纤陀螺小型化设计,具有良好的温度稳定性。(The invention discloses a device and a method for realizing the sensitivity multiplication of a fiber-optic gyroscope based on a multi-core fiber. Light emitted by the wide-spectrum light source is divided into two paths through the optical coupler and the Y-shaped multifunctional integrated optical device, and enters the multi-core optical fiber ring from the fan-in ends of the two fan-in fan-out modules along the clockwise direction and the anticlockwise direction respectively; after the light beams completely pass through the current fiber core, the light beams are guided to the other fiber core by the fan-in fan-out module and spread in the same direction, and the circulation is repeated for a plurality of times until the two light beams pass through all the fiber cores and leave the multi-core fiber ring from the fan-out end; the digital closed-loop signal processing circuit acquires and processes the electric signal of the optical detector to obtain carrier rotating speed information and complete feedback and modulation. The effective optical path length of the fiber-optic gyroscope is several times of the length of the optical fiber ring, so that the Sagnac phase shift and the sensitivity achieve the multiplication effect, and the difficulty and the cost of the winding process of the optical fiber ring can be reduced. The invention is also suitable for the miniaturization design of the fiber-optic gyroscope and has good temperature stability.)

1. A device for realizing the sensitivity multiplication of a fiber-optic gyroscope based on a multi-core fiber is characterized by comprising a wide-spectrum light source (1), an optical coupler (2), a Y-shaped multifunctional integrated optical device (3), a first fan-in fan-out module (4), a second fan-in fan-out module (5), a multi-core fiber ring (6), an optical detector (7), a preamplification circuit (8), an analog-to-digital converter (9), a digital signal processor (10) and a digital-to-analog converter (11);

light emitted by the wide-spectrum light source (1) enters the Y-shaped multifunctional integrated optical device (3) through the optical coupler (2) and is divided into two paths, one path enters the multi-core optical fiber ring (6) from the fan-in port of the first fan-in fan-out module (4) in a clockwise direction, the other path enters the multi-core optical fiber ring (6) from the fan-in port of the second fan-in fan-out module (5) in a counterclockwise direction, after the two beams of light completely pass through the current fiber core, the two beams of light are continuously guided to the next fiber core by the first fan-in fan-out module (4) and the second fan-in fan-out module (5) to propagate in the same direction, the light passes through all fiber cores for many times, finally leaves the multi-core fiber ring through the fan-out port, returns to the Y-shaped multifunctional integrated optical device (3) and is recombined into one path of light, the synthesized light enters the optical detector (7) through the optical coupler (2), and the optical detector (7) converts the received optical signals into electrical signals;

the electric signal output by the optical detector (7) enters a digital signal processor (10) through a preamplification circuit (8) and an analog-to-digital converter (9), the carrier rotating speed information is demodulated by the digital signal processor (10), the carrier rotating speed information is used for gyro output, and meanwhile, a superposed bias signal generates a modulation voltage through a digital-to-analog converter (11) and is loaded into a phase modulator on the Y-shaped multifunctional integrated optical device (3) to realize closed-loop feedback and bias modulation.

2. The device for realizing the sensitivity multiplication of the fiber-optic gyroscope based on the multi-core optical fiber as claimed in claim 1, wherein the wide-spectrum light source (1) adopts a fiber-optic light source, and the wavelength is 1310nm or 1550 nm.

3. The device for realizing the sensitivity multiplication of the fiber-optic gyroscope based on the multi-core optical fiber as claimed in claim 1, wherein the Y-shaped multifunctional integrated optical device (3) is a lithium niobate integrated optical modulator, and is composed of a polarizer, a phase modulator and a Y waveguide.

4. The device for realizing fiber-optic gyroscope sensitivity multiplication based on multicore optical fibers according to claim 1, wherein the first fan-in fan-out module (4) and the second fan-in fan-out module (5) are used for guiding light beams to enter and leave the multicore optical fiber ring (6) and realizing connection among a plurality of cores in the multicore optical fiber ring (6).

5. The device for realizing the sensitivity multiplication of the fiber-optic gyroscope based on the multi-core fiber as claimed in claim 1, wherein the multi-core fiber ring (6) is formed by winding the multi-core polarization maintaining fiber by a four-stage symmetric winding method, the multi-core fiber has a plurality of independent fiber cores in a common cladding region, and the crosstalk between the fiber cores is low.

6. Connection between the cores of a multicore optical fiber ring (6) according to claim 4, characterized in that the optical signals transmitted clockwise and counterclockwise go around the ring with the same number of turns.

7. The multi-core fiber ring (6) wound from multi-core polarization maintaining fibers as claimed in claim 5, wherein the multi-core fiber ring (6) can also be wound from multi-core single mode fibers, but a Lyot depolarizer is added to the device at the front end of each of the first fan-in fan-out block (4) and the second fan-in fan-out block (5).

8. A method for realizing the sensitivity multiplication of a fiber-optic gyroscope based on multi-core optical fibers is characterized in that light emitted by a wide-spectrum light source is divided into two paths through an optical coupler and a Y-shaped multifunctional integrated optical device, and the two paths enter a multi-core optical fiber ring from fan-in ends of two fan-in fan-out modules respectively along the clockwise direction and the anticlockwise direction; after the light beams completely pass through the current fiber core, the light beams are guided to the other fiber core by the fan-in fan-out module and spread in the same direction, and the circulation is repeated for a plurality of times until the two light beams pass through all the fiber cores and leave the multi-core fiber ring from the fan-out end; the digital closed-loop signal processing circuit acquires and processes the electric signal of the optical detector to obtain carrier rotating speed information and complete feedback and modulation.

Technical Field

The invention relates to the technical field of fiber optic gyroscopes, in particular to a device and a method for realizing sensitivity multiplication of a fiber optic gyroscope based on multi-core optical fibers.

Background

The fiber-optic gyroscope is an all-solid-state inertial instrument for measuring the angular velocity of a moving carrier by utilizing the Sagnac effect. Compared with the traditional electromechanical gyro, the fiber optic gyro has the advantages of small volume, low cost, long service life, large dynamic range, short starting time and the like, and is widely applied to the fields of aerospace attitude control, navigation orientation, land navigation, resource exploration and excavation and the like, so that the performance of the fiber optic gyro is further improved, and the fiber optic gyro has important significance on the inertial technology.

For the fiber optic gyroscope, the nonreciprocal phase difference generated by the angular velocity can be accumulated by increasing the length of the sensing fiber loop, so that the sensitivity and the precision of the gyroscope are further improved. However, the increase of the length of the optical fiber not only means larger volume, cost and winding difficulty, but also greatly reduces the adaptability to environmental factors such as temperature and the like, and limits the application scene of the gyroscope. The difficulty in solving this conflict is how to reduce the length of the optical fiber while maintaining the optical path of the light beam.

Multicore fibers are a new type of optical fiber in which multiple individual cores are present in a common cladding region. The multicore fiber with the number of fiber cores of N is assumed to be used as a sensing coil of the fiber optic gyroscope, two beams of light propagating in the forward and reverse directions are enabled to sequentially pass through the N fiber cores, and the corresponding effective optical path is N times of the length of the fiber, namely, theoretically, the same sensitivity can be achieved by 1/N of the length of the common fiber. The connection between the multi-core optical fiber and other optical fibers and each fiber core mainly depends on a fan-in fan-out module, generally adopts a tapering process to realize low insertion loss and crosstalk coupling between cores, and output ports of the multi-core optical fiber correspond to the fiber cores of the multi-core optical fiber one by one.

Disclosure of Invention

The invention solves the technical problems of overcoming the limitations of poor stability and low precision of the optical fiber gyroscope at the present stage, and provides a device and a method for realizing the sensitivity multiplication of the optical fiber gyroscope based on a multi-core optical fiber.

A device for realizing the sensitivity multiplication of a fiber-optic gyroscope based on a multi-core fiber comprises a wide-spectrum light source, an optical coupler, a Y-shaped multifunctional integrated optical device, a first fan-in fan-out module, a second fan-in fan-out module, a multi-core fiber ring, an optical detector, a preamplification circuit, an analog-to-digital converter, a digital signal processor and a digital-to-analog converter; light emitted by the wide-spectrum light source enters the Y-shaped multifunctional integrated optical device through the optical coupler and is divided into two paths, one path of light enters the multi-core optical fiber ring from a fan-in port of the first fan-in fan-out module in a clockwise direction, the other path of light enters the multi-core optical fiber ring from a fan-in port of the second fan-in fan-out module in a counterclockwise direction, two paths of light are guided to the next fiber core through the first fan-in fan-out module and the second fan-in fan-out module after completely passing through the current fiber core and are transmitted in the same direction, the process is repeated for multiple times until passing through all the fiber cores, finally the light returns to the Y-shaped multifunctional integrated optical device after leaving the multi-core optical fiber ring through the fan-out port to be recombined into one path of light, the synthesized light enters the optical detector;

the electric signal output by the optical detector enters a digital signal processor through a preamplification circuit and an analog-to-digital converter, the digital signal processor demodulates carrier rotating speed information, the information is used for gyro output, and simultaneously, a superposed bias signal generates a modulation voltage through the digital-to-analog converter and is loaded into a phase modulator on a Y-shaped multifunctional integrated optical device to realize closed-loop feedback and bias modulation.

The wide-spectrum light source adopts an optical fiber light source, and the wavelength is 1310nm or 1550 nm.

The Y-shaped multifunctional integrated optical device is a lithium niobate integrated optical modulator and consists of a polarizer, a phase modulator and a Y waveguide.

The first fan-in fan-out module and the second fan-in fan-out module are used for guiding light beams to enter and leave the multi-core optical fiber ring and realizing connection among a plurality of fiber cores in the multi-core optical fiber ring, and the number of circles of optical signals transmitted clockwise and anticlockwise in the ring is the same.

The multi-core optical fiber ring is formed by winding a multi-core polarization-maintaining optical fiber by a four-stage symmetrical winding method, a plurality of independent fiber cores exist in a common cladding region of the multi-core optical fiber, and crosstalk among the fiber cores is low; when the multi-core optical fiber ring is wound by multi-core single-mode optical fibers, a Lyot depolarizer is required to be added to the front ends of the first fan-in fan-out module and the second fan-in fan-out module in the device respectively.

A method for realizing the sensitivity multiplication of a fiber-optic gyroscope based on multi-core optical fibers comprises the following steps that light emitted by a wide-spectrum light source is divided into two paths through an optical coupler and a Y-shaped multifunctional integrated optical device, and the two paths enter a multi-core optical fiber ring from fan-in ends of two fan-in fan-out modules respectively along the clockwise direction and the anticlockwise direction; after the light beams completely pass through the current fiber core, the light beams are guided to the other fiber core by the fan-in fan-out module and spread in the same direction, and the circulation is repeated for a plurality of times until the two light beams pass through all the fiber cores and leave the multi-core fiber ring from the fan-out end; the digital closed-loop signal processing circuit acquires and processes the electric signal of the optical detector to obtain carrier rotating speed information and complete feedback and modulation.

Compared with the prior art, the invention has the beneficial effects that:

the optical fiber ring adopted by the invention is formed by winding multi-core optical fibers, and the fiber cores are connected through the fan-in fan-out module, so that light beams are orderly transmitted among the fiber cores, and compared with a common optical fiber gyroscope, the effective length and sensitivity of an optical path can be greatly improved, or the length of the optical fibers is reduced by multiple times under the condition of keeping the same sensitivity. Therefore, the size and the cost of the fiber-optic gyroscope can be optimized by using the multi-core fiber, and the difficulty in winding the fiber-optic ring and errors caused by temperature drift and the like are reduced.

Drawings

FIG. 1 is a schematic structural diagram of an apparatus for implementing sensitivity multiplication of a fiber-optic gyroscope based on a multi-core fiber;

the optical fiber optical coupler comprises a wide-spectrum light source 1, an optical coupler 2, a Y-shaped multifunctional integrated optical device 3, a first fan-in fan-out module 4, a second fan-in fan-out module 5, a multi-core optical fiber ring 6, an optical detector 7, a preamplification circuit 8, an analog-to-digital converter 9, a digital signal processor 10 and a digital-to-analog converter 11.

Fig. 2 is a schematic diagram of the connection of seven-core optical fibers to a fan-in fan-out module.

FIG. 3 is a cross-sectional view of both ends of a seven-core fiber optic ring and the direction of light beam entry and exit from the fiber optic ring;

the ports defining the two ends of the optical fiber are respectively A1, A2, A3, A4, A5, A6, A7 and B1, B2, B3, B4, B5, B6 and B7.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific examples, but the scope of the present invention is not limited to the examples described below.

Referring to fig. 1, a device for realizing fiber-optic gyroscope sensitivity multiplication based on multi-core fiber includes a wide-spectrum light source 1, an optical coupler 2, a Y-shaped multifunctional integrated optical device 3, a first fan-in fan-out module 4, a second fan-in fan-out module 5, a multi-core fiber ring 6, a photodetector 7, a pre-amplification circuit 8, an analog-to-digital converter 9, a digital signal processor 10, and a digital-to-analog converter 11.

Light emitted by a wide-spectrum light source 1 enters a Y-shaped multifunctional integrated optical device 3 after passing through an optical coupler 2 and is divided into two paths, one path of light enters a multi-core optical fiber ring 6 from a fan-in port of a first fan-in fan-out module 4 in a clockwise direction, the other path of light enters the multi-core optical fiber ring 6 from a fan-in port of a second fan-in fan-out module 5 in a counterclockwise direction, two paths of light are guided to the next fiber core continuously by the first fan-in fan-out module 4 and the second fan-in fan-out module 5 after passing through the current fiber core completely, the light is propagated in the same direction, the process is repeated for multiple times until passing through all the fiber cores, finally the light returns to the Y-shaped multifunctional integrated optical device 3 to be recombined after leaving the multi-core optical fiber ring through a fan-out port, the synthesized light enters an optical detector 7 through the optical coupler 2, the optical detector 7 converts received optical signals into electrical signals and enters, the carrier rotating speed information is demodulated by the digital signal processor 10, the information is used for gyro output, and simultaneously, the superposed offset signal generates a modulation voltage through the digital-to-analog converter 11 and is loaded to the phase modulator on the Y-shaped multifunctional integrated optical device 3 to realize closed-loop feedback and offset modulation.

The wide-spectrum light source 1 adopts an erbium-doped superfluorescent optical fiber light source, the wavelength is 1310nm or 1550nm, and the Y-shaped multifunctional integrated optical device 3 is a lithium niobate integrated optical modulator and consists of a polarizer, a phase modulator and a Y waveguide. The multi-core optical fiber ring 6 is formed by winding a seven-core polarization-maintaining optical fiber by a four-stage symmetrical winding method, has the length of 200m, has the adjacent fiber core crosstalk of-50 dB/100km, and is covered with a high-temperature-resistant coating. The first and second fan-in fan-out modules 4 and 5 are used to guide the light beams into and out of the multi-core fiber ring 6 and to make connections between the cores in the multi-core fiber ring 6, and the fan-in fan-out module and the seven-core fiber connection are schematically shown in fig. 2. The connection method of the fiber cores can be various, taking fig. 3 as an example, including but not limited to two-way pigtails connecting a1, B4 and Y-type multifunctional integrated optical device 3 in sequence and B1 and a2, B2 and A3, B3 and A7, B7 and A6, B6 and A5, B5 and A4, when the clockwise light beam passes through a1, B1, a2, B2, A3, B3, A7, B7, A6, B6, A5, B5, A4 and B4 in sequence (cycle 7 times), and the counterclockwise light beam passes through B4, A4, B5, A5, B6, A6, B7, A7, B3, A3, B2, a2, B1 and a1 in sequence (cycle 7 times). The effective optical path of the two beams of light is seven times of the length of the optical fiber, and for clockwise light and anticlockwise light at the same moment, the distance between the fiber cores is close, so that the influence of introducing nonreciprocal phase difference by factors such as stress due to different positions of the fiber cores can be further reduced.

The invention takes the multicore fiber as the fiber ring of the fiber-optic gyroscope, and the fiber cores are connected with each other through the fan-in fan-out module, so that light beams are transmitted among the fiber cores in sequence. Therefore, the multi-core optical fiber can optimize the volume and the cost of the optical fiber gyroscope, reduce the difficulty of optical fiber ring winding and reduce the drift caused by environmental factors such as temperature and the like.

The above embodiments specifically disclose the present invention, and those skilled in the art can utilize the multi-core fiber to increase the effective optical path length of the fiber-optic gyroscope to realize equivalent transformation or modification of sensitivity multiplication according to the teaching and teaching of the present invention, and all such equivalent transformations or modifications are within the scope of the present invention.