WO2024045451A1 - 基于模分复用的光纤陀螺及其精度提升方法 - Google Patents
基于模分复用的光纤陀螺及其精度提升方法 Download PDFInfo
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- G—PHYSICS
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- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/58—Turn-sensitive devices without moving masses
- G01C19/64—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams
- G01C19/72—Gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
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- G—PHYSICS
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- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
- G01D21/02—Measuring two or more variables by means not covered by a single other subclass
Definitions
- This application relates to the field of fiber optic gyroscope application technology, and provides a fiber optic gyroscope based on mode division multiplexing and a method for improving its accuracy.
- Fiber optic gyroscope is an optical sensor based on the Sagnac effect that measures the angular rate of inertial motion of an object. It has many advantages such as simple production process, strong stability, long service life, large dynamic range, and high survival rate. It is becoming more and more popular. It has increasingly become the core angular rate sensitive element used in inertial navigation systems and is widely used in high-precision navigation demand scenarios such as aerospace, aviation and navigation.
- the working principle of the fiber optic gyroscope is that when two beams of homologous light are transmitted in the clockwise and counterclockwise directions in a closed optical path, when the optical path rotates, the two beams of light will produce a phase difference related to the rotation angular rate. This phase difference and the interference signal received by the detector can be used to calculate the rotation angular rate.
- High precision and miniaturization are the development trends of fiber optic gyroscopes and are important directions for the improvement and upgrading of fiber optic gyroscope technology.
- Traditional fiber optic gyroscopes mainly rely on increasing the diameter and length of the fiber optic ring to improve fiber optic gyroscope accuracy, but the size of the fiber optic ring is limited.
- the traditional fiber optic gyroscope uses the Sagnac interference of the fundamental mode inside the ring to achieve sensitivity and demodulation of the angular rate. Its accuracy is easily affected by changes in environmental parameters and optical circuit noise. At the same time, traditional fiber optic gyroscopes are limited by the principle of single-channel signal demodulation, and further noise processing is difficult, such as the processing of the relative intensity noise of the light source and the noise floor of the circuit board.
- dual-polarization fiber optic gyroscope technology multiplexes the two polarization states in the fiber loop, and uses the opposite amplitude characteristics of the polarization errors of the two polarization states to cancel the polarization-related errors, thus significantly Improves gyro stability, but cannot effectively reduce other noise.
- This application aims to solve at least one of the technical problems existing in the related art. To this end, this application proposes a fiber optic gyroscope based on mode division multiplexing to eliminate the impact of external temperature changes on the output of the fiber optic gyroscope and improve the accuracy of the fiber optic gyroscope.
- This application also proposes a method for improving the accuracy of fiber optic gyroscopes based on mode division multiplexing.
- the first embodiment of the present application provides a fiber optic gyroscope based on mode division multiplexing, including:
- a light source generating unit the light source generating unit is used to output fundamental mode light and high-order mode light;
- the first sensing unit includes a first coupling subunit and a first optical fiber loop.
- the first coupling subunit is connected to the first output end of the light source generating unit to receive fundamental mode light and detect the fundamental mode light. The light undergoes coupling processing, and the first optical fiber loop is connected to the first coupling subunit;
- the second sensing unit includes a second coupling sub-unit and a second optical fiber loop.
- the second coupling sub-unit is connected to the second output end of the light source generating unit to receive high-order mode light and perform processing on the high-order mode light. Coupling processing, the second optical fiber loop is connected to the second coupling sub-unit;
- the first optical fiber loop and the second optical fiber loop are used to simultaneously measure temperature and angular rate.
- the light source generating unit includes a wide-spectrum light source and a mode-selective coupler, and the output end of the wide-spectrum light source is connected to the input of the mode-selective coupler.
- the end connection is used to output fundamental mode light to the mode selective coupler, and the mode selective coupler is used to couple part of the fundamental mode light into high-order mode light.
- the mode selective coupler includes a few-mode optical fiber and a single-mode optical fiber, and the single-mode optical fiber is fused and tapered to the few-mode optical fiber, so The input end of the single-mode optical fiber is connected to the wide-spectrum light source, the output end of the single-mode optical fiber is connected to the first coupling sub-unit, and the output end of the few-mode optical fiber is connected to the second coupling sub-unit.
- the first coupling sub-unit includes a first polarization-maintaining fiber coupler and a first Y waveguide, and the input of the first polarization-maintaining fiber coupler The end is connected to the light source generating unit to couple the fundamental mode light, and the input end of the first Y waveguide is connected to the output end of the first polarization-maintaining optical fiber coupler to transmit and modulate the fundamental mode light, so The first Y waveguide is connected to the first optical fiber loop.
- the second coupling sub-unit includes a second polarization-maintaining fiber coupler and a second Y waveguide, and the input of the second polarization-maintaining fiber coupler The end is connected to the light source generating unit for coupling high-order mode light.
- the input end of the second Y waveguide is connected to the output end of the second polarization-maintaining optical fiber coupler for transmitting and modulating high-order mode light.
- Two Y waveguides are connected to the second optical fiber loop.
- the second polarization-maintaining fiber coupler includes a first few-mode fiber and a second few-mode fiber, and the first few-mode fiber and the The second few-mode optical fiber fused tapered connection;
- the second polarization-maintaining optical fiber coupler includes a first multi-mode optical fiber and a second multi-mode optical fiber, and the first multi-mode optical fiber and the second multi-mode optical fiber are fused and tapered.
- the coupling ratio of the input end and the output end of the second polarization-maintaining fiber coupler is 50:50.
- a second embodiment of the present application provides a method for improving the accuracy of a fiber optic gyroscope based on mode division multiplexing, which includes the following steps:
- the method for improving the accuracy of fiber optic gyroscope based on mode division multiplexing also includes the following steps:
- step S40 establishing a two-dimensional sensing matrix specifically includes:
- a two-dimensional matrix is established in which the effective refractive index and angular rate of fundamental mode light and higher-order mode light change with temperature.
- the two-dimensional matrix is demodulated to obtain the fiber optic gyroscope bias stability curve.
- the fiber optic gyroscope based on mode division multiplexing couples and outputs high-order mode light to the second fiber ring through the light source generation unit, and outputs the basic mode light to the first fiber ring.
- the first fiber optic ring and the second fiber optic ring simultaneously measure changes in external temperature and rotation speed, and establish a sensing demodulation matrix to suppress the impact of noise factors such as temperature on the gyro output to solve the limited accuracy of fiber optic gyros in complex temperature environments. problem to meet the application requirements of high-precision long-endurance inertial navigation systems.
- this application provides a method for improving the accuracy of fiber optic gyroscopes based on mode division multiplexing by establishing a two-dimensional sensing matrix in which the effective refractive index and rate error of fundamental mode light and high-order mode light change with temperature, and then the two-dimensional matrix is Demodulation, thereby accurately quantifying the impact of temperature on the output of the fiber optic gyroscope, and obtaining the bias stability curve of the fiber optic gyroscope, thereby effectively overcoming the impact of changes in ambient temperature parameters on the accuracy of the fiber optic gyroscope in complex physical environments, and meeting the application needs of the fiber optic gyroscope system.
- Figure 1 is a schematic structural diagram of a fiber optic gyroscope based on mode division multiplexing provided by an embodiment of the present application
- Figure 2 is a schematic structural diagram of a mode selective coupler provided by an embodiment of the present application.
- Figure 3 is a schematic diagram illustrating the coupling efficiency of the mode selective coupler provided by the embodiment of the present application and the relationship between the energy ratio of the fundamental mode light and the higher-order mode light at the output end and the wavelength;
- Figure 4 is a schematic structural diagram of a second polarization-maintaining optical fiber coupler provided by an embodiment of the present application
- Figure 5 is a schematic diagram of the relationship between the original output curve and temperature change of the fiber optic gyroscope in the prior art
- Figure 6 is a schematic diagram comparing the original output curve of the fiber optic gyroscope based on mode division multiplexing and the optimized output curve of the two-dimensional sensing demodulation matrix provided by the embodiment of the present application.
- connection should be understood in a broad sense.
- it can be a fixed connection or a detachable connection. Or integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium.
- connection should be understood in specific situations.
- the first feature "on” or “below” the second feature may be that the first and second features are in direct contact, or the first and second features are in intermediate contact. Indirect media contact.
- the terms “above”, “above” and “above” the first feature is above the second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature.
- "Below”, “below” and “beneath” the first feature to the second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature has a smaller horizontal height than the second feature.
- references to the terms “one embodiment,” “some embodiments,” “an example,” “specific examples,” or “some examples” or the like means that specific features are described in connection with the embodiment or example. , structures, materials or features are included in at least one embodiment or example of the embodiments of this application. In this specification, the schematic expressions of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification unless they are inconsistent with each other.
- the first embodiment of the present application provides a fiber optic gyroscope based on mode division multiplexing, including:
- a light source generating unit which is used to output fundamental mode light 110 and high-order mode light 120;
- the first sensing unit includes a first coupling sub-unit and a first optical fiber loop 500.
- the first coupling sub-unit is connected to the first output end of the light source generating unit to receive the fundamental mode light 110 and respond to the fundamental mode light 110. Perform coupling processing, and the first optical fiber loop 500 is connected to the first coupling subunit;
- the second sensing unit includes a second coupling sub-unit and a second optical fiber ring 800.
- the second coupling sub-unit is connected to the second output end of the light source generating unit to receive the high-order mode light 120 and couple the high-order mode light 120.
- the second optical fiber loop 800 is connected to the second coupling subunit;
- the first optical fiber loop 500 and the second optical fiber loop 800 are used to simultaneously measure temperature and angular rate. It can be understood that, as shown in FIGS. 1 and 2 , the light source generating unit is used to output two modes of light sources, including fundamental mode light 110 and higher-order mode light 120 .
- the fundamental mode light 110 is transmitted from the light source generating unit to the first coupling sub-unit, is coupled by the first coupling sub-unit, is transmitted to the first optical fiber ring 500, and then passes through the first optical fiber ring 500 to realize the control of temperature and Measurement of Angular Rate.
- the high-order mode light 120 is transmitted from the light source generating unit to the second coupling sub-unit. After coupling processing by the second coupling sub-unit, it is transmitted to the second optical fiber ring 800 and then passes through the second optical fiber ring 800 to achieve temperature and angular rate control. Measurement.
- first sensing unit and the second sensing unit are two mutually independent sensing units and do not interfere with each other, and the first fiber optic ring 500 and the second fiber optic ring 800 are sensitive to temperature and angular rate.
- the fiber optic gyroscope bias stability curve can effectively overcome the impact of changes in ambient temperature parameters on the accuracy of the fiber optic gyroscope in complex physical environments, thereby improving the accuracy of the fiber optic gyroscope.
- the light source generating unit includes a wide-spectrum light source 100 and a mode-selective coupler 200.
- the output end of the wide-spectrum light source 100 is connected to the input end of the mode-selective coupler 200 to output the fundamental mode to the mode-selective coupler 200.
- the mode selective coupler 200 is used to couple and convert part of the fundamental mode light 110 in the received fundamental mode light into higher-order mode light 120 . It can be understood that the broad spectrum light source 100 can output the fundamental mode light 110 and transmit the fundamental mode light 110 to the mode selective coupler 200, and the mode selective coupler 200 has selective coupling and separation functions.
- the fundamental mode light 110 undergoes a refractive index matching coupling effect in the first coupling region 230 of the mode selective coupler 200, so that part of the fundamental mode light 110 is converted into high-order mode light 120, and then the mode selective coupler 200 outputs the unconverted part of the basic mode light 110. Mode light 110 and the converted higher-order mode light 120.
- the mode selective coupler 200 includes a few-mode optical fiber 220 and a single-mode optical fiber 210.
- the single-mode optical fiber 210 is connected to the few-mode optical fiber 220 by fusion tapering, and the input end of the single-mode optical fiber 210 is connected to the wide-spectrum light source 100.
- the output end of the single-mode optical fiber 210 is connected to the first coupling sub-unit, and the output end of the few-mode optical fiber 220 is connected to the second coupling sub-unit. It can be understood that, as shown in FIG. 2 , using the phase matching principle, the mode selective coupler 200 is made of a few-mode optical fiber 220 and a single-mode optical fiber 210 through fusion tapering.
- the input end of the single-mode optical fiber 210 is connected to the wide-spectrum light source 100, so that the fundamental mode light 110 output by the wide-spectrum light source 100 is transmitted to the single-mode optical fiber 210, and the input end of the few-mode optical fiber 220 is closed.
- the middle portion of the few-mode optical fiber 220 and the single-mode optical fiber 210 is a fused tapered connection location, that is, the first coupling region 230 is formed.
- the high-order mode light 120 converted by the first coupling area 230 is transmitted to the at least mode optical fiber 220, and is transmitted to the second coupling sub-unit from the output end of the few mode optical fiber 220; the remaining part of the fundamental mode light 110 is transmitted to the single mode optical fiber 210 , and is transmitted to the first coupler unit through the output end of the single-mode optical fiber 210.
- the mode selective coupler 200 has one input terminal and two output terminals to realize the input of the fundamental mode light 110 and the output of the higher-order mode light 120 and the output of the remaining part of the fundamental mode light 110 .
- the first coupling subunit includes a first polarization-maintaining optical fiber coupler 300 and a first Y-waveguide 400.
- the input end of the first polarization-maintaining optical fiber coupler 300 is connected to the first output end of the light source generating unit.
- the input end of the first Y waveguide 400 is connected to the output end of the first polarization-maintaining optical fiber coupler 300 for transmitting and modulating the fundamental mode light 110.
- the first Y waveguide 400 is connected to the first optical fiber loop. 500 connections.
- the first polarization-maintaining optical fiber coupler 300 is a traditional polarization-maintaining optical fiber coupler
- the first Y-waveguide 400 is a traditional Y-waveguide
- the first optical fiber ring 500 is a traditional polarization-maintaining optical fiber. Circle.
- the fundamental mode light 110 is transmitted from the single-mode optical fiber 210 to the first polarization-maintaining optical fiber coupler 300, and then transmitted to the first Y-waveguide 400 after being coupled by the first polarization-maintaining optical fiber coupler 300.
- the first Y-waveguide 400 pairs the fundamental mode
- the light 110 is transmitted and modulated, and then the fundamental mode light 110 is transmitted to the first optical fiber loop 500, thereby achieving the measurement of temperature and angular rate by the first optical fiber loop 500.
- the second coupling subunit includes a second polarization-maintaining optical fiber coupler 600 and a second Y-waveguide 700.
- the input end of the second polarization-maintaining optical fiber coupler 600 is connected to the second output end of the light source generating unit.
- the input end of the second Y waveguide 700 is connected to the output end of the second polarization-maintaining fiber coupler 600 for transmitting and modulating the high-order mode light 120.
- the second Y waveguide 700 is connected to the second optical fiber ring 800. .
- the input end of the second polarization-maintaining optical fiber coupler 600 is connected to the output end of the few-mode optical fiber 220, so that the high-order mode light 120 is transmitted to the second polarization-maintaining optical fiber coupler 600, and passes through the second polarization-maintaining optical fiber coupler 600.
- the high-order mode light 120 is transmitted to the second Y waveguide 700.
- the high-order mode light 120 is transmitted to the second optical fiber ring 800, thereby realizing
- the second fiber optic loop 800 measures temperature and angular rate simultaneously with the first fiber optic loop 500 .
- the second polarization-maintaining optical fiber coupler 600 includes a first few-mode optical fiber and a second few-mode optical fiber, and the first few-mode optical fiber and the second few-mode optical fiber are fused and tapered;
- the second polarization-maintaining optical fiber coupler 600 includes a first multi-mode optical fiber 610 and a second multi-mode optical fiber 620, and the first multi-mode optical fiber 610 and the second multi-mode optical fiber 620 are connected through fusion and tapering. It can be understood that the second polarization-maintaining optical fiber coupler 600 is prepared by fusion tapering connection of two identical optical fibers. Specifically, few-mode optical fiber or multi-mode optical fiber can be used.
- the second polarization-maintaining optical fiber coupler 600 is prepared by fusion-tapering a first few-mode optical fiber and a second few-mode optical fiber, wherein the middle portion of the first few-mode optical fiber and the middle portion of the second few-mode optical fiber are fused.
- the tapered form forms the coupling zone.
- the second polarization-maintaining optical fiber coupler 600 is prepared by fusion-tapering the first multi-mode optical fiber 610 and the second multi-mode optical fiber 620, wherein the middle part of the first multi-mode optical fiber 610
- the second coupling region 630 is formed with the middle fusion taper of the second multimode optical fiber 620 .
- the coupling ratio of the input end and the output end of the second polarization-maintaining optical fiber coupler 600 is 50:50.
- the second optical fiber ring 800 is prepared by winding, curing, and aging based on few-mode optical fiber or multi-mode optical fiber.
- a detector 900 is also included.
- the detection end of the detector 900 is connected to the output end of the light source generating unit. Specifically, the detection end of the detector 900 is respectively connected to the output of the single-mode optical fiber 210. The end is connected to the output end of the few-mode optical fiber 220 to receive the interference signal and then calculate the angular rate.
- a second embodiment of the present application provides a method for improving the accuracy of a fiber optic gyroscope based on mode division multiplexing, which includes the following steps:
- the method for improving the accuracy of fiber optic gyroscope based on mode division multiplexing also includes the following steps:
- step S40 establishing a two-dimensional sensing matrix specifically includes:
- a two-dimensional matrix is established in which the effective refractive index and angular rate of the fundamental mode light 110 and the high-order mode light 120 change with temperature, and the two-dimensional matrix is demodulated to obtain the fiber optic gyro bias stability curve.
- the embodiment of the present application provides a method for improving the accuracy of fiber optic gyroscope based on mode division multiplexing, which specifically includes the following steps:
- the mode selective coupler 200 in the form of the fundamental mode, that is, the fundamental mode light 110, and uses the phase matching coupling principle in the first coupling region 230:
- A(z) is the energy distribution of the fundamental mode light
- B(z) is the energy distribution of the higher-order mode light
- ⁇ aa is the self-coupling coefficient of the fundamental mode light
- ⁇ bb is the self-coupling coefficient of the higher-order mode light
- ⁇ ab is Mutual coupling coefficient of fundamental mode light
- ⁇ ba is the mutual coupling coefficient of higher-order mode light
- ⁇ a is the propagation constant of fundamental mode light
- ⁇ b is the propagation constant of higher-order mode light
- z is the coupling length of few-mode fiber and single-mode fiber.
- Part of the fundamental mode light 110 is converted into high-order mode light 120 through the first coupling region 230, creating basic conditions for the expansion of mode division multiplexing technology in fiber optic gyroscopes.
- the self-coupling coefficients ⁇ aa and ⁇ bb can be ignored, the mutual coupling coefficient ⁇ ab ⁇ ⁇ ba , and the mutual coupling coefficient can be expressed as:
- the remaining part of the fundamental mode light 110 will sensitively measure temperature and angular rate in the first fiber loop 500 constructed of a traditional polarization-maintaining fiber; the high-order mode light 120 will be in Temperature and angular rate are sensitively measured in the second fiber loop 800 constructed of mode fiber or multimode fiber.
- the mode selective coupler 200 can have good conversion performance within the working range of the fiber optic gyroscope; wherein, the degree of fusion between the single-mode optical fiber 210 and the few-mode optical fiber 220 is:
- Z is the width of the end face structure of the first coupling zone 230; when the melting degree is 1, it means that the single-mode optical fiber 210 and the few-mode optical fiber 220 are completely fused; when the melting degree is 2, it means that the single-mode optical fiber 210 and the few-mode optical fiber 220 are completely fused. There is no fusion between mode fiber 220.
- the single-mode optical fiber 210 uses a standard optical fiber, model SMF-28e; the selected few-mode optical fiber 220 has a parameter of 18/125 ⁇ m.
- the fiber diameters of the single-mode optical fiber 210 and the few-mode optical fiber 220 are 4.0 ⁇ m and 6.15 ⁇ m respectively, the conversion of the fundamental mode light 110 to the high-order mode light 120 can be achieved.
- the coupling efficiency of the mode selective coupler 200 and the energy ratio of the basic mode light 110 and the high-order mode light 120 at the output end change with the wavelength.
- the curve corresponding to the arrow pointing to the left is the mode selective coupler. 200 coupling efficiency changes with wavelength.
- the curve corresponding to the arrow pointing to the right is the change of the energy ratio of fundamental mode light 110 and higher-order mode light 120 with wavelength.
- the melting degree is 1.78
- the width of the end surface structure of the first coupling region 230 is 18.2 ⁇ m.
- the coupling efficiency of the mode selective coupler 200 is close to 0.5.
- the fundamental mode light 110 The energy ratio to high-order mode light 120 is close to 0.9, which can meet the application requirements of fiber optic gyroscopes for mode division multiplexing.
- the second polarization-maintaining optical fiber coupler 600 is prepared by using a few-mode optical fiber or a multi-mode optical fiber to draw a fused taper to ensure low-loss transmission of the high-order mode light 120.
- the drawing process is the same as that of a traditional optical fiber coupler.
- Figure 5 is a schematic diagram illustrating the relationship between the original output curve and the temperature change of the fiber optic gyroscope in the prior art, specifically the relationship between the zero bias curve and the temperature change of the original fiber optic gyroscope.
- Figure 6 is a schematic diagram based on Comparison diagram of the original output curve of the fiber optic gyroscope with mode division multiplexing and the optimized output curve of the two-dimensional sensing demodulation matrix, specifically after establishing the mode effective refractive index and angular rate two-dimensional matrix demodulation based on mode division multiplexing
- the horizontal axis is time in 100s; the left vertical axis is angular rate in °/h; the right vertical axis is temperature in degrees Celsius.
- ⁇ 01 (t) is the output angular rate of fundamental mode light
- ⁇ 11 (t) is the output angular rate of higher-order mode light
- DL is the product of the diameter and length of the fiber loop
- n 01 is the effective rate of fundamental mode light.
- n 11 is the effective refractive index of higher-order mode light; is the coefficient of change of the effective refractive index of fundamental mode light with temperature; is the coefficient of change of the effective refractive index of high-order mode light with temperature; T'(z,t) is the temperature change derivative of the loop; it needs to be explained that due to the diameter and length of the first fiber loop and the second fiber loop are all the same, therefore, DL is the measurement fixed value, and D is the diameter of the fiber loop; L is the length of the fiber loop.
- the effect of temperature on the output of the fiber optic gyroscope is accurately demodulated, thereby improving the bias stability of the fiber optic gyroscope.
- the accuracy of the fiber optic gyroscope is improved from the existing 0.02°/h to 0.003°/h.
- the fiber optic gyroscope based on mode division multiplexing couples and outputs high-order mode light to the second fiber ring through the light source generation unit, and outputs the basic mode light to the first fiber ring.
- the first fiber optic ring and the second fiber optic ring simultaneously measure changes in external temperature and rotation speed, and establish a sensing demodulation matrix to suppress the impact of noise factors such as temperature on the gyro output to solve the limited accuracy of fiber optic gyros in complex temperature environments. problem to meet the application requirements of high-precision long-endurance inertial navigation systems.
- this application provides a method for improving the accuracy of fiber optic gyroscopes based on mode division multiplexing by establishing a two-dimensional sensing matrix in which the effective refractive index and rate error of fundamental mode light and high-order mode light change with temperature, and then the two-dimensional matrix is Demodulation, thereby accurately quantifying the impact of temperature on the output of the fiber optic gyroscope, and obtaining the bias stability curve of the fiber optic gyroscope, thereby effectively overcoming the impact of changes in ambient temperature parameters on the accuracy of the fiber optic gyroscope in complex physical environments, and meeting the application needs of the fiber optic gyroscope system.
- the device embodiments described above are only illustrative.
- the units described as separate components may or may not be physically separated.
- the components shown as units may or may not be physical units, that is, they may be located in one place. , or it can be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Persons of ordinary skill in the art can understand and implement the method without any creative effort.
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Abstract
一种基于模分复用的光纤陀螺及其精度提升方法。基于模分复用的光纤陀螺包括光源发生单元，用以输出基模光（110）和高阶模光（120）；第一传感单元包括第一耦合子单元和第一光纤环圈（500），第一耦合子单元用以接收基模光（110），并对基模光（110）进行耦合处理；第二传感单元包括第二耦合子单元和第二光纤环圈（800），第二耦合子单元用以接收高阶模光（120），并对高阶模光（120）进行耦合处理；第一光纤环圈（500）和第二光纤环圈（800）用以同步测量温度和角速率。基于模分复用的光纤陀螺抑制温度等噪声因素对陀螺输出的影响，解决复杂温度环境下光纤陀螺的精度受限问题，满足高精度长航时惯性导航系统应用需求。
Description
相关申请
本申请要求2022年09月01日递交的申请号为202211059471.0，发明名称为“基于模分复用的光纤陀螺及其精度提升方法”的中国发明专利申请的优先权，其全部内容以引用方式并入本文。
本申请涉及光纤陀螺应用技术领域，提供一种基于模分复用的光纤陀螺及其精度提升方法。
光纤陀螺是基于萨格奈克效应制作的一种测量物体惯性运动角速率的光学传感器，因其具备生产工艺简单、稳定性强、使用寿命长、动态范围大、成活率高等诸多优势，越来越多地成为用于惯性导航系统的核心角速率敏感元件，广泛应用于航天、航空及航海等高精度导航需求场景。
光纤陀螺的工作原理是，在闭合光路中两束同源光分别沿着顺时针方向和逆时针方向传输时，当光路存在转动时两束光会产生与该转动角速率相关的相位差，结合该相位差和探测器接收到的干涉信号可以解算出转动角速率。高精度、小型化是光纤陀螺的发展趋势，是光纤陀螺技术改进和升级的重要方向，传统的光纤陀螺主要依靠增大光纤环圈的直径和长度来提高光纤陀螺精度，但是光纤环圈尺寸的增加往往会增大噪声水平，尤其是径向温度Shupe效应导致的陀螺漂移更难克服，因此环圈尺寸增加方案并不能有效提升光纤陀螺的精度。
传统的光纤陀螺是利用基模在环圈内部的萨格奈克干涉，实现对角速率的敏感和解调，其精度容易受到环境参数变化和光路电路噪声的影响。同时，传统的光纤陀螺受单路信号解调原理的限制，进一步的噪声处理存在较大的难度，比如光源的相对强度噪声和线路板底噪的处理等。
为了解决光纤陀螺中的偏振交叉耦合噪声，双偏振光纤陀螺技术将光纤环圈中的两个偏振态进行复用，利用两个偏振态偏振误差的振幅相反的特点对消偏振相关误差，从而大幅提升陀螺稳定性，但是不能实现对其他噪声的有效降低。
发明内容
本申请旨在至少解决相关技术中存在的技术问题之一。为此，本申请提出一种基于模分复用的光纤陀螺，实现消除外界温度变化对光纤陀螺输出的影响，提高光纤陀螺的使用精度。
本申请还提出一种基于模分复用的光纤陀螺的精度提升方法。
本申请第一方面实施例提供一种基于模分复用的光纤陀螺，包括：
光源发生单元，所述光源发生单元用以输出基模光和高阶模光；
第一传感单元，包括第一耦合子单元和第一光纤环圈，所述第一耦合子单元与所述光源发生单元的第一输出端连接，用以接收基模光，并对基模光进行耦合处理，所述第一光纤环圈与所述第一耦合子单元连接；
第二传感单元，包括第二耦合子单元和第二光纤环圈，所述第二耦合子单元与所述光源发生单元的第二输出端连接，用以接收高阶模光，并对高阶模光进行耦合处理，所述第二光纤环圈与所述第二耦合子单元连接；
其中，所述第一光纤环圈和所述第二光纤环圈用以同步测量温度和角速率。
根据本申请第一方面实施例的基于模分复用的光纤陀螺，所述光源发生单元包括宽谱光源和模式选择耦合器，所述宽谱光源的输出端与所述模式选择耦合器的输入端连接，用以向所述模式选择耦合器输出基模光，所述模式选择耦合器用以将部分基模光耦合转化为高阶模光。
根据本申请第一方面实施例的基于模分复用的光纤陀螺，所述模式选择耦合器包括少模光纤和单模光纤，所述单模光纤与所述少模光纤熔融拉锥连接，所述单模光纤的输入端与所述宽谱光源连接，所述单模光纤的输出端与所述第一耦合子单元连接，所述少模光纤的输出端与所述第二耦合子单元连接。
根据本申请第一方面实施例的基于模分复用的光纤陀螺，所述第一耦合子单元包括第一保偏光纤耦合器和第一Y波导，所述第一保偏光纤耦合器的输入端与所述光源发生单元连接，用以耦合基模光，所述第一Y波导的输入端与所述第一保偏光纤耦合器的输出端连接，用以传输和调制基模光，所述第一Y波导与所述第一光纤环圈连接。
根据本申请第一方面实施例的基于模分复用的光纤陀螺，所述第二耦合子单元包括第二保偏光纤耦合器和第二Y波导，所述第二保偏光纤耦合器的输入端与所述光源发生单元连接，用以耦合高阶模光，所述第二Y波导的输入端与所述第二保偏光纤耦合器的输出端连接，用以传输和调制高阶模光，所述第二Y波导与所述第二光纤环圈连接。
根据本申请第一方面实施例的基于模分复用的光纤陀螺，所述第二保偏光纤耦合器包括第一少模光纤和第二少模光纤，所述第一少模光纤和所述第二少模光纤熔融拉锥连接；
或，所述第二保偏光纤耦合器包括第一多模光纤和第二多模光纤，所述第一多模光纤与所述第二多模光纤熔融拉锥连接。
根据本申请第一方面实施例的基于模分复用的光纤陀螺，所述第二保偏光纤耦合器的输入端和输出端的耦合比为50:50。
本申请第二方面实施例提供一种基于模分复用的光纤陀螺的精度提升方法，包括如下步骤：
S10、基于模分复用原理，调控模式选择耦合器中的少模光纤和单模光纤的熔融度以及直径参数，以调整模式选择耦合器的工作带宽和高阶模式耦合效率；
S20、调控第二保偏光纤耦合器中的两根光纤的熔融度，以实现第二保偏光纤耦合器的输入端和输入端的耦合比为50:50；
S30、采用少模光纤或多模光纤制备第二光纤环圈；
S40、对光纤陀螺进行温度性能测试，建立二维传感矩阵，并消除外界温度变化对光纤陀螺精度的影响。
根据本申请第二方面实施例的基于模分复用的光纤陀螺的精度提升方法，还包括如下步骤：
S11、通过模式选择耦合器利用相位匹配方法对部分基模光进行耦合，并输出基模光和高阶模光。
根据本申请第二方面实施例的基于模分复用的光纤陀螺的精度提升方法，所述S40步骤中，建立二维传感矩阵具体包括：
基于模分复用原理，建立基模光和高阶模光的有效折射率和角速率随温度变化的二维矩阵，对二维矩阵解调，获得光纤陀螺零偏稳定性曲线。
本申请实施例中的上述一个或多个技术方案，至少具有如下技术效果之一：
本申请提供的基于模分复用的光纤陀螺，通过光源发生单元耦合输出高阶模光至第二光纤环圈，并将基模光输出至第一光纤环圈中。第一光纤环圈和第二光纤环圈同步测量外界温度和转速变化，建立传感解调矩阵，从而抑制温度等噪声因素对陀螺输出的影响，以解决复杂温度环境下光纤陀螺的精度受限问题，满足高精度长航时惯性导航系统应用需求。
进一步地，本申请提供的基于模分复用的光纤陀螺的精度提升方法，通过建立基模光与高阶模光的有效折射率与速率误差随温度变化的二维传感矩阵，并对二维矩阵解调，从而精确地量化温度对光纤陀螺输出的影响，获得了光纤陀螺零偏稳定性曲线，从而有力地克服复杂物理环境下环境温度参数变化对光纤陀螺精度的影响，满足光纤陀螺系统应用需求。
本申请的附加方面和优点将在下面的描述中部分给出，部分将从下面的描述中变得明显，或通过本申请的实践了解到。
为了更清楚地说明本申请实施例或相关技术中的技术方案，下面将对实施例或相关技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请实施例提供的基于模分复用的光纤陀螺的示意性结构图；
图2是本申请实施例提供的模式选择耦合器的示意性结构图；
图3是本申请实施例提供的模式选择耦合器的耦合效率以及输出端基模光与高阶模光的能量比与波长的变化关系的示意图；
图4是本申请实施例提供的第二保偏光纤耦合器的示意性结构图；
图5是现有技术中光纤陀螺的原始输出曲线与温度变化关系示意图；
图6是本申请实施例提供的基于模分复用的光纤陀螺的原始输出曲线与二维传感解调矩阵优化后的输出曲线的对比示意图。
附图标记：
100、宽谱光源；110、基模光；120、高阶模光；200、模式选择耦合器；210、单模光纤；220、少模光纤；230、第一耦合区；300、第一保偏光纤耦合器；400、第一Y波导；500、第一光纤环圈；600、第二保偏光纤耦合器；610、第一多模光纤；620、第二多模光纤；630、第二耦合区；700、第二Y波导；800、第二光纤环圈；900、探测器。
下面结合附图和实施例对本申请的实施方式作进一步详细描述。以下实施例用于说明本申请，但不能用来限制本申请的范围。
在本申请实施例的描述中，需要说明的是，术语“中心”、“纵向”、“横向”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。此外，术语“第一”、“第二”、“第三”仅用于描述目的，而不能理解为指示或暗示相对重要性。
在本申请实施例的描述中，需要说明的是，除非另有明确的规定和限定，术语“相连”、“连接”应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连。对于本领域的普通技术人员而言，可以具体情况理解上述术语在本申请实施例中的具体含义。
在本申请实施例中，除非另有明确的规定和限定，第一特征在第二特征“上”或“下”可以是第一和第二特征直接接触，或第一和第二特征通过中间媒介间接接触。而且，第一特征在第二特征“之上”、“上方”和“上面”可是第一特征在第二特征正上方或斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”可以是第一特征在第二特征正下方或斜下方，或仅仅表示第一特征水平高度小于第二特征。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本申请实施例的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
如图1至图6所示，本申请第一方面实施例提供一种基于模分复用的光纤陀螺，包括：
光源发生单元，光源发生单元用以输出基模光110和高阶模光120；
第一传感单元，包括第一耦合子单元和第一光纤环圈500，第一耦合子单元与光源发生单元的第一输出端连接，用以接收基模光110，并对基模光110进行耦合处理，第一光纤环圈500与第一耦合子单元连接；
第二传感单元，包括第二耦合子单元和第二光纤环圈800，第二耦合子单元与光源发生单元的第二输出端连接，用以接收高阶模光120，并对高阶模光120进行耦合处理，第二光纤环圈800与第二耦合子单元连接；
其中，第一光纤环圈500和第二光纤环圈800用以同步测量温度和角速率。可以理解的是，如图1和图2所示，其中，光源发生单元用以输出两种模式的光源，包括基模光110和高阶模光120。
进一步地，基模光110由光源发生单元传输至第一耦合子单元，经第一耦合子单元耦合处理，传输至第一光纤环圈500，进而通过第一光纤环圈500，实现对温度和角速率的测量。
其中，高阶模光120由光源发生单元传输至第二耦合子单元，经第二耦合子单元耦合处理，传输至第二光纤环圈800，进而通过第二光纤环圈800，实现对温度和角速率的测量。
需要说明的是，第一传感单元和第二传感单元为两个相互独立的传感单元，互不发生干扰，且第一光纤环圈500和第二光纤环圈800对温度和角速率进行同步测量，建立基模光与高阶模光的有效折射率与速率误差随温度变化的二维传感矩阵，并对二维矩阵解调，从而精确地量化温度对光纤陀螺输出的影响，获得了光纤陀螺零偏稳定性曲线，从而有力地克服复杂物理环境下环境温度参数变化对光纤陀螺精度的影响，进而提高光纤陀螺精度。
在一些实施例中，光源发生单元包括宽谱光源100和模式选择耦合器200，宽谱光源100的输出端与模式选择耦合器200的输入端连接，用以向模式选择耦合器200输出基模光110。模式选择耦合器200用以将接收的基模光中的部分基模光110耦合转化为高阶模光120。可以理解的是，宽谱光源100可输出基模光110，并将基模光110传输至模式选择耦合器200中，模式选择耦合器200具有选择耦合和分离作用。
其中，基模光110在模式选择耦合器200的第一耦合区230发生折射率匹配耦合效应，使得部分基模光110转化为高阶模光120，进而模式选择耦合器200输出未被转化的部分基模光110和转化成的高阶模光120。
在一些实施例中，模式选择耦合器200包括少模光纤220和单模光纤210，单模光纤210与少模光纤220熔融拉锥连接，单模光纤210的输入端与宽谱光源100连接，单模光纤210的输出端与第一耦合子单元连接，少模光纤220的输出端与第二耦合子单元连接。可以理解的是，如图2所示，利用相位匹配原理，模式选择耦合器200由少模光纤220和单模光纤210通过熔融拉锥制备而成。具体的，单模光纤210的输入端与宽谱光源100连接，实现宽谱光源100输出的基模光110传输至单模光纤210，少模光纤220的输入端封闭。少模光纤220和单模光纤210的中部为熔融拉锥连接位置，即形成第一耦合区230。
其中，由第一耦合区230转化形成的高阶模光120传输至少模光纤220，并由少模光纤220的输出端传输至第二耦合子单元；剩余部分的基模光110传输至单模光纤210，并由单模光纤210的输出端传输至第一耦合子单元。
也就是说，模式选择耦合器200具有一个输入端和两个输出端，实现基模光110的输入以及高阶模光120的输出和剩余部分的基模光110的输出。
在一些实施例中，第一耦合子单元包括第一保偏光纤耦合器300和第一Y波导400，第一保偏光纤耦合器300的输入端与光源发生单元的第一输出端连接，用以耦合基模光110，第一Y波导400的输入端与第一保偏光纤耦合器300的输出端连接，用以传输和调制基模光110，第一Y波导400与第一光纤环圈500连接。可以理解的是，如图1所示，第一保偏光纤耦合器300为传统的保偏光纤耦合器，第一Y波导400为传统的Y波导，第一光纤环圈500为传统保偏光纤环圈。其中，基模光110由单模光纤210传输至第一保偏光纤耦合器300，经第一保偏光纤耦合器300耦合作用后传输至第一Y波导400，第一Y波导400对基模光110进行传输和调制，之后将基模光110传输至第一光纤环圈500，进而实现第一光纤环圈500对温度和角速率的测量。
在一些实施例中，第二耦合子单元包括第二保偏光纤耦合器600和第二Y波导700，第二保偏光纤耦合器600的输入端与光源发生单元的第二输出端连接，用以耦合高阶模光120，第二Y波导700的输入端与第二保偏光纤耦合器600的输出端连接，用以传输和调制高阶模光120，第二Y波导700与第二光纤环圈800连接。可以理解的是，如图1所示，第二保偏光纤耦合器600的输入端与少模光纤220的输出端连接，实现高阶模光120传输至第二保偏光纤耦合器600内，经过第二保偏光纤耦合器600的耦合作用，高阶模光120传输至第二Y波导700，经第二Y波导700高阶模式的传输和调制， 高阶模光120传输至第二光纤环圈800，进而实现第二光纤环圈800与第一光纤环圈500同步测量温度和角速率。
在一些实施例中，第二保偏光纤耦合器600包括第一少模光纤和第二少模光纤，第一少模光纤和第二少模光纤熔融拉锥连接；
或，第二保偏光纤耦合器600包括第一多模光纤610和第二多模光纤620，第一多模光纤610与第二多模光纤620熔融拉锥连接。可以理解的是，第二保偏光纤耦合器600由两根相同的光纤进行熔融拉锥连接制备。具体的，可选用少模光纤或多模光纤。
在一个实施例中，第二保偏光纤耦合器600由第一少模光纤和第二少模光纤熔融拉锥连接制备，其中，第一少模光纤的中部和第二少模光纤的中部熔融拉锥形成耦合区。
在一个实施例中，如图4所示，第二保偏光纤耦合器600由第一多模光纤610与第二多模光纤620熔融拉锥连接制备，其中，第一多模光纤610的中部与第二多模光纤620的中部熔融拉锥形成第二耦合区630。
在一些实施例中，第二保偏光纤耦合器600的输入端和输出端的耦合比为50:50。
在一个实施例中，第二光纤环圈800基于少模光纤或多模光纤进行绕制、固化、老化制备而成。
在一些实施例中，如图1所示，还包括探测器900，探测器900的探测端与光源发生单元的输出端连接，具体的，探测器900的探测端分别与单模光纤210的输出端和少模光纤220的输出端连接，用以接收干扰信号，进而解算角速率。
本申请第二方面实施例提供一种基于模分复用的光纤陀螺的精度提升方法，包括如下步骤：
S10、基于模分复用原理，调控模式选择耦合器200中的少模光纤220和单模光纤210的熔融度以及直径参数，以调整模式选择耦合器200的工作带宽和高阶模式耦合效率；
S20、调控第二保偏光纤耦合器600中的两根光纤的熔融度，以实现第二保偏光纤耦合器600的输入端和输入端的耦合比为50:50；
S30、采用少模光纤或多模光纤制备第二光纤环圈800；
S40、对光纤陀螺进行温度性能测试，建立二维传感矩阵，并消除外界温度变化对光纤陀螺精度的影响。
根据本申请第二方面实施例的基于模分复用的光纤陀螺的精度提升方法，还包括如下步骤：
S11、通过模式选择耦合器200利用相位匹配方法对部分基模光110进行耦合，并输出基模光110和高阶模光120。
根据本申请第二方面实施例的基于模分复用的光纤陀螺的精度提升方法，S40步骤中，建立二维传感矩阵具体包括：
基于模分复用原理，建立基模光110和高阶模光120的有效折射率和角速率随温度变化的二维矩阵，并对该二维矩阵解调，以获得光纤陀螺零偏稳定性曲线。
本申请实施例提供的一种基于模分复用的光纤陀螺的精度提升方法，具体包括如下步骤：
S10、依据模分复用原理，对模式选择耦合器200进行优化设计。通过对单模光纤和少模光纤之间熔融度、单模光纤和少模光纤各自的直径的精确控制，调整模式选择耦合器200的工作带宽和高阶模式的耦合效率；
S11、通过模式选择耦合器200利用相位匹配方法对部分基模光110进行耦合，并输出基模光110和高阶模光120；
具体的，光从宽谱光源100中发出以后以基模形式即基模光110，进入模式选择耦合器200，在第一耦合区230利用相位匹配耦合原理：
式中，A(z)为基模光的能量分布；B(z)为高阶模光的能量分布；κ
aa为基模光的自耦合系数；κ
bb为高阶模光的自耦合系数；κ
ab为基模光的互耦合系数；κ
ba为高阶模光的互耦合系数；β
a为基模光的传播常数；β
b为高阶模光的传播常数；z为少模光纤和单模光纤的耦合长度。
通过第一耦合区230将部分基模光110转化为高阶模光120，为模分复用技术在光纤陀螺中的拓展创造基本条件。
其中，自耦合系数κ
aa和κ
bb可以忽略，互耦合系数κ
ab≈κ
ba，互耦合系数可以表示为：
式中，
为基模光的光场分布；E
b是高阶模光的光场分布；Δε为微扰系数；ω是光频率。
在部分基模光110转化为高阶模光120后，剩余部分的基模光110将在由传统保偏光纤构建的第一光纤环圈500中敏感测量温度和角速率；高阶模光120将在由少模光纤或多模光纤构建的第二光纤环圈800中敏感测量温度和角速率。
具体的，通过精确控制单模光纤210的直径X和少模光纤220的直径Y以及单模光纤210与少模光纤220之间的熔融度，以实现基模光110到高阶模光120的转换，且使模式选择耦合器200能够在光纤陀螺工作范围内具备很好的转换性能；其中，单模光纤210与少模光纤220之间的熔融度为：
式中，Z为第一耦合区230端面结构的宽度；当熔融度为1时，代表单模光纤210与少模光纤220间完全熔融；当熔融度为2时，代表单模光纤210与少模光纤220间没有熔融。本实施例中，单模光纤210采用的是标准光纤，型号为SMF-28e；选用的少模光纤220的参数为18/125μm，。经过充分的理论计算和实际拉制流程，当单模光纤210与少模光纤220的纤径分别为4.0μm和6.15μm时，能够实现基模光110向高阶模光120的转换。
在实际操作过程中，首先剥去单模光纤210与少模光纤220的涂覆层并用酒精将剥去涂覆层后的去单模光纤与少模光纤擦拭干净；然后将单模光纤210预拉至83μm，再将少模光纤220和预拉好的单模光纤210平行放置到一起，扭转一圈后平稳放置到氢氧拉锥机位移平台上，利用火焰加热的方式对单模光纤210与少模光纤220进行弱熔融拉锥；其中，单模光纤210的输入端连接可调谐激光器，输出端连接功率计；少模光纤220的输出端连接电荷耦合器件以观察输出模场，当观测到纯净的高阶模光120且分光比达到要求后停止拉锥并进行封装。
如图3所示模式选择耦合器200的耦合效率以及输出端基模光110与高阶模光120的能量比随波长的变化关系，图3中，指向左侧的箭头对应的曲线为模式选择耦合器200的耦合效率随波长的变化曲线，指向右侧箭头对应的曲线为基模光110与高阶模光120的能量比随波长的变化曲线。当熔融度为1.78时，此时第一耦合区230端面结构的宽度为18.2μm，在光纤陀螺工作波段范围1520nm-1560nm内，模式选择耦合器200的 耦合效率接近0.5，同时，基模光110与高阶模光120的能量比接近0.9，能够满足模分复用的光纤陀螺应用需求。
S20、调控第二保偏光纤耦合器600中的两根光纤的熔融度，以实现第二保偏光纤耦合器600的输入端和输入端的耦合比为50:50；
具体的，采用少模光纤或者多模光纤拉熔融拉锥制备第二保偏光纤耦合器600，以保证高阶模光120的低损耗传输，拉制流程与传统光纤耦合器一致，当耦合分光比为1:1时即可满足应用需求。
S30、采用少模光纤或多模光纤进行绕制、固化、老化制备第二光纤环圈800。需要说明的是，第一光纤环圈500和第二光纤环圈800的直径和长度均相同。
S40、将宽谱光源100、模式选择耦合器200、第一保偏光纤耦合器300、第一Y波导400、第一光纤环圈500、第二保偏光纤耦合器600、第二Y波导700、第二光纤环圈800和探测器900装配成光纤陀螺，并对光纤陀螺开展温度性能测试，建立二维传感矩阵消除外界温度变化对陀螺精度的影响，提高光纤陀螺使用精度；具体的，如图5和图6所示，图5示意为现有技术中光纤陀螺的原始输出曲线与温度变化关系示意图，具体地为原始光纤陀螺的零偏曲线与温度的变化关系，图6示意为基于模分复用的光纤陀螺的原始输出曲线与二维传感解调矩阵优化后的输出曲线的对比示意图，具体的为基于模分复用建立模式有效折射率、角速率二维矩阵解调以后的光纤陀螺零偏稳定性曲线与现有技术中光纤陀螺的原始输出曲线的对比。其中，横轴为时间，单位为100s；左竖轴为角速率，单位为°/h；右竖轴为温度，单位为摄氏度。
通过建立热瞬变过程引起的旋转速率误差矩阵：
式中，Ω
01(t)为基模光的输出角速率；Ω
11(t)为高阶模光的输出角速率；DL为光纤环圈的直径与长度的乘积；n
01为基模光的有效折射率；n
11为高阶模光的有效折射率；
为基模光的有效折射率随温度的变化系数；
为高阶模光的有效折射率随温度的变化系数；T'(z,t)为环圈的温度变化导数；需要解释说明的是，由于第一光纤环圈和第二光纤环圈的直径和长度均相同，因此，DL为测量定值，且D为光纤环圈的直径；L为光纤环圈的长度。
利用基模光110与高阶模光120的有效折射率随温度的变化以及速率误差随温度导数的变化关系，精确解调出温度对光纤陀螺输出的影响，从而提升光纤陀螺的零偏稳定性，经过本实施例的方法，光纤陀螺精度由现有的0.02°/h提升至0.003°/h。
本申请提供的基于模分复用的光纤陀螺，通过光源发生单元耦合输出高阶模光至第二光纤环圈，并将基模光输出至第一光纤环圈中。第一光纤环圈和第二光纤环圈同步测量外界温度和转速变化，建立传感解调矩阵，从而抑制温度等噪声因素对陀螺输出的影响，以解决复杂温度环境下光纤陀螺的精度受限问题，满足高精度长航时惯性导航系统应用需求。
进一步地，本申请提供的基于模分复用的光纤陀螺的精度提升方法，通过建立基模光与高阶模光的有效折射率与速率误差随温度变化的二维传感矩阵，并对二维矩阵解调，从而精确地量化温度对光纤陀螺输出的影响，获得了光纤陀螺零偏稳定性曲线，从而有力地克服复杂物理环境下环境温度参数变化对光纤陀螺精度的影响，满足光纤陀螺系统应用需求。
以上所描述的装置实施例仅仅是示意性的，其中作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部模块来实现本实施例方案的目的。本领域普通技术人员在不付出创造性的劳动的情况下，即可以理解并实施。
最后应说明的是：以上实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的精神和范围。
Claims (10)
- 一种基于模分复用的光纤陀螺，其特征在于，包括：光源发生单元，所述光源发生单元用以输出基模光和高阶模光；第一传感单元，包括第一耦合子单元和第一光纤环圈，所述第一耦合子单元与所述光源发生单元的第一输出端连接，用以接收基模光，并对基模光进行耦合处理，所述第一光纤环圈与所述第一耦合子单元连接；第二传感单元，包括第二耦合子单元和第二光纤环圈，所述第二耦合子单元与所述光源发生单元的第二输出端连接，用以接收高阶模光，并对高阶模光进行耦合处理，所述第二光纤环圈与所述第二耦合子单元连接；其中，所述第一光纤环圈和所述第二光纤环圈用以同步测量温度和角速率。
- 根据权利要求1所述的基于模分复用的光纤陀螺，其特征在于，所述光源发生单元包括宽谱光源和模式选择耦合器，所述宽谱光源的输出端与所述模式选择耦合器的输入端连接，用以向所述模式选择耦合器输出所述基模光，所述模式选择耦合器用以将部分所述基模光耦合转化为所述高阶模光。
- 根据权利要求2所述的基于模分复用的光纤陀螺，其特征在于，所述模式选择耦合器包括少模光纤和单模光纤，所述单模光纤与所述少模光纤熔融拉锥连接，所述单模光纤的输入端与所述宽谱光源连接，所述单模光纤的输出端与所述第一耦合子单元连接，所述少模光纤的输出端与所述第二耦合子单元连接。
- 根据权利要求1所述的基于模分复用的光纤陀螺，其特征在于，所述第一耦合子单元包括第一保偏光纤耦合器和第一Y波导，所述第一保偏光纤耦合器的输入端与所述光源发生单元连接，用以耦合所述基模光，所述第一Y波导的输入端与所述第一保偏光纤耦合器的输出端连接，用以传输和调制所述基模光，所述第一Y波导与所述第一光纤环圈连接。
- 根据权利要求1所述的基于模分复用的光纤陀螺，其特征在于，所述第二耦合子单元包括第二保偏光纤耦合器和第二Y波导，所述第二保偏光纤耦合器的输入端与所述光源发生单元连接，用以耦合所述高阶模光，所述第二Y波导的输入端与所述第二保偏光纤耦合器的输出端连接，用以传输和调制所述高阶模光，所述第二Y波导与所述第二光纤环圈连接。
- 根据权利要求5所述的基于模分复用的光纤陀螺，其特征在于，所述第二保偏光纤耦合器包括第一少模光纤和第二少模光纤，所述第一少模光纤和所述第二少模光纤熔融拉锥连接；或，所述第二保偏光纤耦合器包括第一多模光纤和第二多模光纤，所述第一多模光纤与所述第二多模光纤熔融拉锥连接。
- 根据权利要求5所述的基于模分复用的光纤陀螺，其特征在于，所述第二保偏光纤耦合器的输入端和输出端的耦合比为50:50。
- 一种如权利要求1至7任一项所述的基于模分复用的光纤陀螺的精度提升方法，其特征在于，包括如下步骤：S10、基于模分复用原理，调控模式选择耦合器中的少模光纤和单模光纤的熔融度以及直径参数，以调整所述模式选择耦合器的工作带宽和高阶模式耦合效率；S20、调控第二保偏光纤耦合器中的两根光纤的熔融度，以实现第二保偏光纤耦合器的输入端和输入端的耦合比为50:50；S30、采用所述少模光纤或所述多模光纤制备第二光纤环圈；S40、对所述光纤陀螺进行温度性能测试，建立二维传感矩阵，并消除外界温度变化对光纤陀螺精度的影响。
- 根据权利要求8所述的基于模分复用的光纤陀螺的精度提升方法，其特征在于，还包括如下步骤：S11、通过所述模式选择耦合器利用相位匹配方法对部分基模光进行耦合，并输出基模光和高阶模光。
- 根据权利要求8所述的基于模分复用的光纤陀螺的精度提升方法，其特征在于，所述S40步骤中，建立二维传感矩阵具体包括：基于所述模分复用原理，建立基模光和高阶模光的有效折射率和角速率随温度变化的二维矩阵，并对所述二维矩阵解调，以获得所述光纤陀螺零偏稳定性曲线。
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