A fiber-optic gyroscope integrated special device

Abstract

The application discloses a kind of special devices for fiber-optic gyroscope integration, including wide spectrum light source, two light beam shaping modules, four mode spot converters, two couplers, three polarizers, modulation electrode, optical path adjustment waveguide and detector, device is formed by second mode spot converter and third mode spot converter two input and output ports, for connecting fiber-optic gyroscope ring.The advantages of the application are that the light source, coupler, Y waveguide and detector required by the traditional fiber-optic gyroscope are integrated into one device, which not only greatly reduces the size of the fiber-optic gyroscope, but also helps to improve the reliability of the fiber-optic gyroscope.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical fiber sensing application, and particularly relates to a special device for optical fiber gyroscope integration. BACKGROUND

[0002] The optical fiber gyroscope is a kind of all-solid-state gyroscope based on the optical Sagnac effect, and is a basic and core component for realizing autonomous navigation, positioning and orientation of a carrier. Compared with a mechanical gyroscope, the optical gyroscope has advantages of wide precision range, no rotating and friction components, small size, light weight, high reliability and the like. After nearly six decades of development, the optical fiber gyroscope has gradually become a mainstream device of an inertial navigation system, and has been widely applied to the fields of aviation, aerospace, navigation, weapons, energy and the like, forming full coverage from commercial level, tactical level and low-precision application to navigation level and strategic level and high-precision application. Under the new situation, a new generation of inertial navigation system is continuously developed towards miniaturization and low cost, and higher and higher requirements are put forward for the comprehensive performance of the gyroscope such as size, precision, cost and the like.

[0003] The interference optical gyroscope is mainly composed of a wide-spectrum light source, an isolator, a coupler, a first beam shaping module, a second beam shaping module, a first mode spot converter, a second mode spot converter, a third mode spot converter, a fourth mode spot converter, a first polarizer, a second polarizer, a third polarizer, a modulation electrode, an optical path adjustment waveguide and a detector. The interference optical gyroscope is mainly composed of a wide-spectrum light source, an isolator, a coupler, a first beam shaping module, a second beam shaping module, a Y waveguide integrating functions of a beam splitter, a beam combiner, a polarizer, a phase modulator, a passive sensing loop and a detector and the like. At present, the interference optical gyroscope system is mainly built by using discrete devices, and the devices are coupled through optical fibers. The system built by using the discrete devices can freely select the devices with optimal performance, but end face reflection, coupling loss and polarization noise caused by axis error and the like are inevitably introduced, thereby reducing the performance of the device. In addition, the system built by using the discrete devices increases the cost of manual coupling, and cannot realize batch production. Meanwhile, the traditional scheme is difficult to realize miniaturization of the optical fiber gyroscope due to the large size and independent packaging of the optical devices and the optical fiber ring with a length of hundreds or thousands of meters. Therefore, it is urgent to explore a new technical scheme to effectively integrate different functions of the optical path, greatly reduce the volume of the optical path of the gyroscope, improve the process compatibility and reduce the manufacturing cost of the device. SUMMARY

[0004] The present application is directed to the deficiencies of the prior art, and proposes a special device for optical fiber gyroscope integration.

[0005] One of the above-mentioned purposes of the present application is realized by the following technical scheme:

[0006] A special device for optical fiber gyroscope integration, comprising a wide-spectrum light source, a first beam shaping module, a second beam shaping module, a first mode spot converter, a second mode spot converter, a third mode spot converter, a fourth mode spot converter, a first coupler, a second coupler, a first polarizer, a second polarizer, a third polarizer, a modulation electrode, an optical path adjustment waveguide and a detector.

[0007] The wide spectrum light source and the first mode spot converter, the detector and the fourth mode spot converter are connected by free space for light transmission; the first mode spot converter and the second mode spot converter, the first mode spot converter and the third mode spot converter, the second mode spot converter and the fourth mode spot converter, the third mode spot converter and the fourth mode spot converter are connected by optical waveguide for light transmission;

[0008] The wide spectrum light source is used for generating high polarization degree light;

[0009] The first light beam shaping module is used for shaping the high polarization degree light, so that the light mode field is changed to the size of the corresponding light mode field of the mode spot converter;

[0010] The first mode spot converter is used for converting the go light output by the first light beam shaping module into a light mode field matched with the size of the optical waveguide and then entering the optical waveguide;

[0011] The first coupler is used for transmitting the go light to the first polarization filter and coupling the return light into the fourth mode spot converter;

[0012] The first polarization filter is used for performing polarization filtering on the go light and the return light, filtering out the TM mode and retaining the TE mode;

[0013] The second coupler is used for splitting the go light into two beams of equal power and combining the two return beams;

[0014] The modulation electrode is used for performing optical phase modulation on the two go beams and the two return beams by applying voltage;

[0015] The second polarizer and the third polarizer are used for performing second polarization filtering on the two go beams after optical phase modulation and performing re-polarization filtering on the two return beams;

[0016] The optical path adjustment waveguide is used for adjusting the optical path of one go beam after the second polarization filtering and adjusting the optical path of one return beam;

[0017] The second mode spot converter is used for converting the one go beam after optical path modulation into a light mode field matched with the fiber mode field, outputting the go light, and inputting the return light; the second mode spot converter is provided with a go light output interface and a return light input interface, and is used for connecting the fiber optic gyroscope ring;

[0018] The third mode spot converter is used for converting the other go beam after the second polarization filtering into a light mode field matched with the fiber mode field, outputting the go light, and inputting the return light; the third mode spot converter is provided with a go light output interface and a return light input interface, and is used for connecting the fiber optic gyroscope ring.

[0019] The fourth mode spot converter is used for optical mode field conversion of the back light output by the first coupler;

[0020] The second light beam shaping module is used for further shaping of the back light output by the fourth mode spot converter;

[0021] The detector is used for detecting the light intensity information of the back light output by the second light beam shaping module.

[0022] Moreover, the wide-spectrum light source is a high-polarization light source, the TE mode power is greater than the TM mode power, the polarization degree is greater than 10 dB, and the spectral width is greater than 40 nm.

[0023] Moreover, the first light beam shaping module is composed of two parallel microlenses, and the second light beam shaping module is composed of one microlens.

[0024] Moreover, the first polarizer is a bend waveguide type polarizer, which is used for realizing the polarization filtering function and the light waveguide turning of the device.

[0025] Moreover, the second polarizer and the third polarizer are waveguide coupling type polarizers, the two ends of which are strip waveguide input ends and output ends, and the middle is a hybrid waveguide coupling polarizing section, the hybrid waveguide coupling polarizing section is a three-layer structure, the lowermost layer of the waveguide is lithium niobate with high refractive index, the middle layer is silica with low refractive index, and the upper metal layer is selected from chromium.

[0026] Moreover, the difference between the optical path of the optical path adjustment waveguide and the optical path of the straight waveguide is greater than the coherence length of the wide-spectrum light source.

[0027] Moreover, the coupler is a multimode interference coupler or a Y-branch coupler.

[0028] Moreover, the modulation electrode adopts a push-pull structure.

[0029] Moreover, the mode spot converter adopts a tapered structure.

[0030] Moreover, the light waveguide, the two couplers, the first polarizer and the four mode spot converters are all made of lithium niobate material.

[0031] The application has the advantages and positive effects that:

[0032] 1. Compared with the traditional discrete fiber-optic gyroscope system, the fiber-optic gyroscope integrated special device of the application integrates the four discrete optical devices required in the traditional technical solution into one device, and greatly reduces the device size on the basis of keeping the original functions unchanged.

[0033] 2、The optical fiber gyro integrated special device of the application realizes no optical fiber of the device, avoids end face reflection, coupling loss and polarization noise caused by axis error, etc.

[0034] 3、The optical fiber gyro integrated special device of the application reduces artificial coupling cost and realizes batch production. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a structure schematic diagram of the optical fiber gyro integrated special device of the application;

[0036] Figure 2 is a structure schematic diagram of the bend waveguide type polarizer of the application;

[0037] Figure 3 is a structure schematic diagram of the waveguide coupling type polarizer of the application;

[0038] Figure 4 is a structure schematic diagram of the Y branch coupler of the application;

[0039] Figure 5 is a structure schematic diagram of the mode spot converter of the application. DETAILED DESCRIPTION

[0040] The structure of the application is further described below in combination with the drawings and through examples. It should be noted that the examples are narrative and not restrictive.

[0041] The application provides an optical fiber gyro integrated special device, please refer to Figures 1-4 The application point is: comprising a wide spectrum light source 1, a first light beam shaping module 2, a second light beam shaping module 14, a first mode spot converter 3, a second mode spot converter 11, a third mode spot converter 12, a fourth mode spot converter 13, a first coupler 4, a second coupler 6, a first polarizer 5, a second polarizer 8, a third polarizer 9, a modulation electrode 7, an optical path adjustment waveguide 10 and a detector 15.

[0042] During operation, the highly polarized light emitted by the broadband light source 1 (constituting the outgoing beam) is shaped by the first beam shaping module 2, and the optical mode field is transformed to the size of the optical mode field corresponding to the mode field converter. The shaped outgoing beam is converted into an optical mode field matching the size of the optical waveguide by the first mode field converter 3 and then enters the optical waveguide. After passing through the first coupler 4, it is polarized and filtered by the first polarizer 5 to filter out the TM mode and retain the TE mode, thereby improving the extinction ratio of the light. Subsequently, it is split into two outgoing beams of equal power by the second coupler 6. After applying a voltage to the modulation electrode 7, the optical phase of the two outgoing beams is modulated. The two modulated outgoing beams pass through the second polarizer 8 and the third polarizer 9 respectively to achieve a second polarization filtering, further improving the extinction ratio. One of the outgoing beams passes through the optical path adjustment waveguide 10 to adjust the optical path and is then converted into an optical mode field matching the optical fiber mode field by the second mode field converter 11. In the application of this integrated special device, the second mode field converter 11 is connected to one end of the optical fiber loop of the optical fiber gyroscope. The other outgoing beam is converted into an optical mode field matching the optical fiber mode field by the third mode converter 12. In the application of this integrated dedicated device, the third mode converter 12 is connected to the other end of the optical fiber loop of the optical fiber gyroscope. After the two outgoing beams are transmitted in the optical fiber loop, they return and enter the optical waveguide path again through the third mode converter 12 and the second mode converter 11 respectively. After passing through the third polarizer 9 and the second polarizer 8 and the modulation electrode 7 respectively, the two beams are combined into a return beam by the second coupler 6. The combined return beam passes through the first polarizer 5 and is coupled to the fourth mode converter 13 by the first coupler 4. After the fourth mode converter 13 performs optical mode field conversion, it enters the second beam shaping module 14 for further shaping. Finally, the detector 15 detects the light intensity information. Among them, the light between the broadband light source 1 and the first mode converter 3, and between the detector 15 and the fourth mode converter 13, is transmitted in free space, while the light between the first mode converter 3 and the second mode converter 11, between the first mode converter 3 and the third mode converter 12, between the second mode converter 11 and the fourth mode converter 13, and between the third mode converter 12 and the fourth mode converter 13 is transmitted in the optical waveguide.

[0043] In this embodiment, the first beam shaping module 2 consists of two parallel microlenses, and the second beam shaping module 14 consists of one microlens, which adjusts the shape of the emitted light spot and improves the coupling efficiency.

[0044] In this embodiment, a high polarization light source is used as a broadband light source. The TE mode power is greater than the TM mode power, the polarization degree is >10dB, and the spectral width is >40nm, providing a light source basis for the high extinction ratio of the entire device.

[0045] In the embodiment, the first polarizer 5 is a curved waveguide type polarizer, as shown in the accompanying drawing (2), which realizes the polarization filtering function of the device by increasing the polarization waveguide outside the transmission waveguide using the different effective refractive indexes of TM mode and TE mode, and improves the extinction ratio on the basis of the high extinction ratio light source, and the curved waveguide is used for light waveguide turning, thereby reducing the volume of the whole device.

[0046] In the embodiment, the second polarizer 8 and the third polarizer 9 are waveguide coupling type polarizers, as shown in the accompanying drawing (3), the lowermost high refractive index material of the waveguide is lithium niobate, the middle low refractive index material is silicon dioxide, and the upper metal layer is chromium which has large absorption loss, and the whole can be divided into three parts, the two ends are strip waveguide input / output ends, and the middle is a hybrid waveguide coupling polarizing section. Due to the special waveguide structure parameters, when the signal light is transmitted, the TE mode is transmitted along the strip waveguide, the TM mode is efficiently separated from the TE mode, and is completely coupled into the hybrid waveguide on both sides and is completely absorbed and lost, and finally only the TE mode can pass through, thereby achieving the effect of polarization and realizing polarization filtering and further improving the extinction ratio of the device.

[0047] In the embodiment, the difference between the optical path of the optical path adjustment waveguide between the second polarizer and the second mode spot converter and the straight waveguide optical path between the third polarizer and the third mode spot converter is more than 200 mu m, which is much larger than the coherence length of the light source, thereby effectively reducing the backscattering noise generated by the device when applied to a gyroscope; the coupler adopts a multimode interference coupling structure or a Y branch coupler for realizing beam splitting / combining function, as shown in the accompanying drawing (4); the modulation electrode adopts a push-pull structure to reduce the modulation driving voltage; the mode spot converter adopts a tapered structure to realize mode field matching, as shown in the accompanying drawing (5). The optical waveguide, the coupler, the polarizer and the mode spot converter are all composed of lithium niobate material.

[0048] In summary, the optical fiber gyroscope integrated special device in the embodiment realizes the full integration of the optical fiber gyroscope optical path device, has the functions of light emission, beam splitting, polarization, modulation and detection of discrete devices, and is helpful to realize the miniaturization, low cost and high reliability of the micro optical fiber gyroscope.

Claims

1. A dedicated integrated fiber optic gyroscope device, characterized in that: The wide-spectrum light source, the first beam shaping module, the second beam shaping module, the first mode spot converter, the second mode spot converter, the third mode spot converter, the fourth mode spot converter, the first coupler, the second coupler, the first polarizer, the second polarizer, the third polarizer, the modulation electrode, the optical path adjustment waveguide and the detector are included. The wide-spectrum light source and the first mode spot converter, the detector and the fourth mode spot converter are connected through free space for light transmission; the first mode spot converter and the second mode spot converter, the first mode spot converter and the third mode spot converter, the second mode spot converter and the fourth mode spot converter, and the third mode spot converter and the fourth mode spot converter are connected through optical waveguide for light transmission. The wide-spectrum light source is used for generating high-polarization light. The first beam shaping module is used for shaping the high-polarization light, so that the light mode field is changed to the size of the corresponding light mode field of the mode spot converter. The first mode spot converter is used for converting the go-light output by the first beam shaping module into a light mode field matching the size of the optical waveguide, and then entering the optical waveguide. The first coupler is used for transmitting the go-light to the first polarizer filter, and coupling the return light into the fourth mode spot converter. The first polarizer is used for polarizing filtering of the go-light and the return light, filtering out the TM mode and retaining the TE mode. The second coupler is used for splitting the go-light into two beams of equal power, and combining the two return beams. The modulation electrode is used for phase modulation of the two go-beams and the two return beams by applying voltage. The second polarizer and the third polarizer are used for second polarization filtering of the two go-beams after phase modulation, and for re-polarization filtering of the two return beams. The optical path adjustment waveguide is used for adjusting the optical path of one of the two go-beams after the second polarization filtering, and adjusting the optical path of one of the two return beams. The second mode spot converter is used for converting the one go-beam after the optical path adjustment into a light mode field matching the fiber mode field, and outputting the go-light, and inputting the return light. The second mode spot converter is used for converting the one go-beam after the optical path adjustment into a light mode field matching the fiber mode field, and outputting the go-light, and inputting the return light. The third mode spot converter is used for converting the other go-beam after the second polarization filtering into a light mode field matching the fiber mode field, and outputting the go-light, and inputting the other return light. The fourth mode spot converter is used for converting the return light output by the first coupler into a light mode field. The second beam shaping module is used for further shaping the return light output by the fourth mode spot converter. The detector is used for detecting the light intensity information of the return light output by the second beam shaping module.

2. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The wide-spectrum light source is a high-polarization light source, the TE mode power is greater than the TM mode power, the polarization degree is greater than 10 dB, and the spectral width is greater than 40 nm.

3. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The first beam shaping module is composed of two parallel microlenses, and the second beam shaping module is composed of one microlens.

4. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The first polarizer is a curved waveguide type polarizer, which is used to realize the polarization filtering function and light waveguide turning of the device.

5. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The second polarizer and the third polarizer are waveguide coupling type polarizers, both ends of which are strip waveguide input ends and output ends, and the middle is a hybrid waveguide coupling polarizing section, which is a three-layer structure, the lowermost layer of the waveguide is lithium niobate with high refractive index, the middle layer is silica with low refractive index, and the upper metal layer is selected from chromium.

6. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The difference between the optical path of the optical path adjustment waveguide and the optical path of the straight waveguide is greater than the coherence length of the wide spectrum light source.

7. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The coupler is a multimode interference coupler or a Y-branch coupler.

8. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The modulation electrode adopts a push-pull structure.

9. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The mode spot converter adopts a tapered structure.

10. The fiber-optic gyroscope integrated application-specific device of claim 1, wherein: The optical waveguide, the two couplers, the first polarizer and the four mode spot converters are all made of lithium niobate material.

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