Low-electric-crosstalk three-axis integrated fiber-optic gyroscope integrated device and fiber-optic gyroscope

Abstract

The invention provides a low-electric-crosstalk three-axis integrated fiber-optic gyroscope integrated device and a fiber-optic gyroscope, and relates to the technical field of optoelectronic devices. According to the invention, the laser chip, the lens group, the waveguide coupler, the lithium niobate Y waveguide modulator group, the detector group and the circuit board are all packaged in the shell, so that the optoelectronic device with high integration level is formed. In the device, the waveguide coupler comprises the coupler base, the one-to-three beam splitter and the three couplers, the one-to-three beam splitter and the three couplers are arranged on the coupler base, the functions of four devices in the prior art can be achieved through one waveguide coupler, the size of the whole device is greatly reduced, and then the size of the fiber-optic gyroscope can be reduced.

Description

Technical Field

[0001] This application relates to the field of optoelectronic device technology, specifically to a low-electrical-crosstalk triaxial integrated fiber optic gyroscope device and a fiber optic gyroscope. Background Technology

[0002] Fiber optic gyroscope systems have important applications in aerospace, inertial navigation, and unmanned platforms. However, their traditional structure relies on multiple discrete optical and electronic components, resulting in large size, complex assembly, and limited reliability. With the development of micro-nano manufacturing and optoelectronic integration technologies, miniaturization and lightweighting of systems have become clear technological trends. Especially in emerging fields such as drones, robots, portable devices, and microsatellites, higher requirements are placed on the size, weight, and power consumption of inertial measurement units. Traditional fiber optic gyroscope transceiver modules (excluding the sensitive ring) are assembled from discrete components such as SLDs, couplers, photodetectors, and circuit boards, with each component interconnected by optical fibers. Due to the limitations of the volume of discrete components and the bending radius of optical fibers, the overall module size is large and cannot meet the development needs of miniaturized systems. To address the above problems, existing patent document CN 118960711 B proposes a low-crosstalk optoelectronic co-packaged triaxial integrated transceiver module. Through the layout and arrangement of the light source component, the first to sixth beam splitting prisms, and the lithium niobate thin-film waveguide chip, it completes the functions of beam splitting, beam combining, polarization, and modulation of optical signals. In the aforementioned existing patent literature, three detectors are designed along the transmission path of the optical signal to be measured, enabling the detection and photoelectric conversion of the signal. Since the optical signal carries information about the current to be measured, the current to be measured can be obtained by analyzing the electrical signal output by the detectors through a processing circuit. However, this structure requires multiple beam splitters, resulting in a relatively large number of components, leaving room for further reduction in size. Summary of the Invention

[0003] The technical problem to be solved by this application is that the modules in the existing fiber optic gyroscope system are relatively large and difficult to further miniaturize. Therefore, this application provides a three-axis integrated fiber optic gyroscope device and fiber optic gyroscope with low electrical crosstalk.

[0004] In a first aspect, the technical solution of this application provides a low-electrical-crosstalk triaxial integrated fiber optic gyroscope device, including a packaging housing, the packaging housing including a substrate and a cover, the substrate being provided with:

[0005] Laser chips are used to emit signal light; The lens group, including a collimating lens and a focusing lens, is arranged along the propagation direction of the signal light to collimate and focus the signal light; A waveguide coupler includes a coupler base, and a beam splitter, a first coupler, a second coupler, and a third coupler disposed on the coupler base. The input end of the beam splitter receives focused signal light, the first output end outputs a split first signal light, the second output end outputs a split second signal light, and the third output end outputs a split third signal light. A first branch of the first coupler is connected to the first output end, the second branch serves as an output end, and the main branch serves as a first transceiver end. A first branch of the second coupler is connected to the second output end, the second branch serves as an output end, and the main branch serves as a second transceiver end. A first branch of the third coupler is connected to the third output end, the second branch serves as an output end, and the main branch serves as a third transceiver end. A lithium niobate Y-waveguide modulator group includes: a first lithium niobate Y-waveguide modulator, the signal end of which is connected to the first transceiver end, and the external end of which is connected to an optical fiber sensitive ring via a polarization-maintaining fiber; a second lithium niobate Y-waveguide modulator, the signal end of which is connected to the second transceiver end, and the external end of which is connected to an optical fiber sensitive ring via a polarization-maintaining fiber; and a third lithium niobate Y-waveguide modulator, the signal end of which is connected to the third transceiver end, and the external end of which is connected to an optical fiber sensitive ring via a polarization-maintaining fiber. The detector group includes: a first detector that detects the induced light signal at the output of a first coupler and processes it into a first electrical signal; a second detector that detects the induced light signal at the output of a second coupler and processes it into a second electrical signal; and a third detector that detects the induced light signal at the output of a third coupler and processes it into a third electrical signal. The circuit board has a signal processing circuit on it, which receives and analyzes the first electrical signal, the second electrical signal and the third electrical signal transmitted by the detector group.

[0006] Preferably, the low electrical crosstalk triaxial integrated fiber optic gyroscope further includes: A cooler, located at the bottom of the laser chip, is used to control the temperature of the laser chip to remain within a set temperature range.

[0007] Preferably, in the low electrical crosstalk triaxial integrated fiber optic gyroscope device, the first detector, the second detector, and the third detector are all back-illuminated detectors; the first detector, the second detector, and the third detector are disposed on the coupler base, and the optical detection surfaces of the three detectors are respectively disposed on the three coupler output terminals.

[0008] Preferably, in the low electrical crosstalk triaxial integrated fiber optic gyroscope device, the first detector, the second detector, and the third detector are all front-illuminated detectors; the first detector, the second detector, and the third detector are disposed on the substrate, and the light detection surfaces of the three detectors are respectively opposite to the output terminals of the three couplers.

[0009] Preferably, in the low electrical crosstalk triaxial integrated fiber optic gyroscope device, the waveguide coupler in which: the first branch of the first coupler shares the same optical transmission channel as the first output end of the splitter; and the first branch of the second coupler shares the same optical transmission channel as the second output end of the splitter.

[0010] Preferably, in the low electrical crosstalk triaxial integrated fiber optic gyroscope device, the lithium niobate Y-waveguide modulator group consists of: the first lithium niobate Y-waveguide modulator, the second lithium niobate Y-waveguide modulator, and the third lithium niobate Y-waveguide modulator, which are independently configured.

[0011] Preferably, in the low electrical crosstalk triaxial integrated fiber optic gyroscope device, each lithium niobate Y-waveguide modulator in the lithium niobate Y-waveguide modulator group is arranged in a direction perpendicular to the substrate.

[0012] Preferably, the low-electrical-crosstalk triaxial integrated fiber optic gyroscope further includes: an isolation cavity disposed above the waveguide coupler, and a circuit board disposed within the cavity of the isolation cavity; each detector in the detector group is electrically connected to the signal processing circuit on the circuit board via a wire.

[0013] Preferably, in the low electrical crosstalk triaxial integrated fiber optic gyroscope device, the isolation cavity is made of a magnetic shielding material, which includes a metal.

[0014] Secondly, the present application provides a fiber optic gyroscope, including the low electrical crosstalk triaxial integrated fiber optic gyroscope device described in any one of the first aspects.

[0015] The technical solution provided in this application has the following technical effects compared with the prior art: This application provides a low-electrical-crosstalk triaxial integrated fiber optic gyroscope device and a fiber optic gyroscope, which encapsulates a laser chip, lens group, waveguide coupler, lithium niobate Y-waveguide modulator group, detector group, and circuit board within a housing, forming a highly integrated optoelectronic device. In this device, the waveguide coupler includes a coupler base, a beam splitter and three couplers mounted on the coupler base, enabling the functionality of four devices in the prior art to be achieved through a single waveguide coupler, significantly reducing the overall device size and thus the size of the fiber optic gyroscope. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a conventional fiber optic gyroscope. Figure 2 This is a schematic diagram of the internal structure of the low electrical crosstalk triaxial integrated fiber optic gyroscope device according to an embodiment of this application, excluding the cover. Figure 3 This is a schematic diagram of the internal structure of the low electrical crosstalk triaxial integrated fiber optic gyroscope device according to one embodiment of this application, including the cover. Figure 4 This is a schematic diagram of the waveguide coupler according to one embodiment of this application; Figure 5 This is a schematic diagram of the structure of a Y-waveguide modulator according to one embodiment of this application. Detailed Implementation

[0017] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0018] It is readily understood that, based on the technical solution of this application, various structural and implementation methods can be interchanged by those skilled in the art without altering the essential spirit of this application. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this application and should not be considered as the entirety of this application or as limitations or restrictions on the technical solution of the application.

[0019] Figure 1The diagram shows the structure of a conventional fiber optic gyroscope. The core of a fiber optic gyroscope is the use of the Sagnac effect to detect rotational angular velocity. A fiber optic gyroscope system consists of: a light source, a coupler, a Y-waveguide, electrodes for phase modulation of the optical signal within the Y-waveguide, fiber optic sensing rings, a detector, a signal source, a signal processing circuit, and a communication line for outputting measurement results. In the fiber optic gyroscope, there are three fiber optic sensing rings, arranged orthogonally in pairs. Light emitted from the light source enters the Y-waveguide integrated optical device through the coupler and is split into two beams of equal intensity, propagating clockwise and counterclockwise in the fiber optic sensing rings, respectively. When the entire fiber optic gyroscope rotates around the central axis of the sensing rings, the optical path lengths of the two counter-rotating beams differ: the beam with the same direction of rotation travels a longer path, while the beam with the opposite direction of rotation travels a shorter path. This path difference translates into a phase difference between the two beams, and the magnitude of this phase difference is proportional to the rotational angular velocity. A signal source drives electrodes on the Y-waveguide, introducing specific phase modulation into the two beams of light. This converts the slight phase difference into a detectable change in light intensity, improving detection sensitivity. After propagation, the two beams re-converge in the Y-waveguide, interfering with each other. The intensity of the interference light changes with the phase difference. The detector converts the interference intensity signal into an electrical signal. The signal processing unit demodulates and processes this signal, ultimately calculating the rotational angular velocity and outputting the measurement result.

[0020] This application provides a low-electrical-crosstalk triaxial integrated fiber optic gyroscope device, such as... Figure 2 and Figure 3 As shown, the device includes a packaging housing, which comprises a substrate 10 and a cover (not shown). The substrate 10 and the cover can be fabricated using conventional optoelectronic device packaging materials. The substrate 10 is provided with: a laser chip 1, a lens group, a waveguide coupler 4, a circuit board 5, a detector group 6, and a lithium niobate Y-waveguide modulator group 8. Specifically: Laser chip 1 is used to emit signal light.

[0021] The lens group, including a collimating lens 31 and a focusing lens 32, is arranged along the propagation direction of the signal light to collimate and focus the signal light.

[0022] like Figure 4As shown, the waveguide coupler 4 includes a coupler base; a 1-to-3 beam splitter 41 and three 1-to-2 couplers 42 disposed on the coupler base, the three couplers being defined as the first coupler, the second coupler, and the third coupler, respectively; wherein, the 1-to-3 beam splitter 41 includes an input end and three output ends, used to split the beam received at the input end into three equal beams. In this scheme, the input end of the 1-to-3 beam splitter 41 receives the focused signal light, the first output end outputs the first signal light after beam splitting, the second output end outputs the second signal light after beam splitting, and the third output end outputs the third signal light after beam splitting; the first branch of the first coupler is connected to the first output end, the second branch serves as its output end, and the main branch serves as the first transceiver end; the first branch of the second coupler is connected to the second output end, the second branch serves as its output end, and the main branch serves as the second transceiver end; the first branch of the third coupler is connected to the third output end, the second branch serves as its output end, and the main branch serves as the third transceiver end.

[0023] The lithium niobate Y-waveguide modulator group 8 includes three lithium niobate Y-waveguide modulator groups. The first lithium niobate Y-waveguide modulator has its signal end connected to the first transceiver end, and its external end connected to a fiber optic sensing loop in the first direction via a polarization-maintaining fiber 9. The second lithium niobate Y-waveguide modulator has its signal end connected to the second transceiver end, and its external end connected to a fiber optic sensing loop in the second direction via a polarization-maintaining fiber 9. The third lithium niobate Y-waveguide modulator has its signal end connected to the third transceiver end, and its external end connected to a fiber optic sensing loop in the third direction via a polarization-maintaining fiber 9. As mentioned above, the first, second, and third directions are three pairs of orthogonal directions, corresponding to the X-axis, Y-axis, and Z-axis of a three-dimensional coordinate system, respectively.

[0024] The detector group 6 includes: a first detector that detects the induced light signal at the output of the first coupler and processes it into a first electrical signal; a second detector that detects the induced light signal at the output of the second coupler and processes it into a second electrical signal; and a third detector that detects the induced light signal at the output of the third coupler and processes it into a third electrical signal.

[0025] Circuit board 5 is provided with a signal processing circuit, which receives and analyzes the first electrical signal, the second electrical signal, and the third electrical signal transmitted by the detector group. The analysis and processing of the first, second, and third electrical signals by the signal processing circuit can refer to the analysis method of existing fiber optic gyroscopes. This application mainly focuses on improvements in device miniaturization and does not involve improvements to the analysis method; therefore, the analysis method will not be described in detail in this application.

[0026] The solution in the above embodiments encapsulates the laser chip 1, lens group, waveguide coupler 4, circuit board 5, detector group 6, and lithium niobate Y-waveguide modulator group 8 within a housing, forming a highly integrated optoelectronic device. In this device, the waveguide coupler 4 includes a coupler base and a beam splitter 41 and three couplers 42 disposed on the coupler base. This allows the functionality of four devices in the prior art to be achieved through a single waveguide coupler 4, significantly reducing the overall device size and further reducing the size of the fiber optic gyroscope.

[0027] Furthermore, such as Figure 2 and Figure 3 As shown, the low electrical crosstalk triaxial integrated fiber optic gyroscope further includes a cooler 2, disposed at the bottom of the laser chip 1, used to control the temperature of the laser chip 1 to maintain it within a set temperature range. Specifically, the cooler 2 can employ thermoelectric cooling (TEC) technology to achieve directional heat transfer through the thermoelectric effect. The cooler 2 is equipped with a temperature sensor (such as a thermistor) to achieve a closed-loop control by monitoring the stability of the laser chip 1. It detects the temperature of the laser chip 1 in real time and dynamically adjusts the cooling power to stabilize the temperature of the laser chip 1 within the set range (such as 25℃±0.1℃), thereby avoiding problems such as wavelength drift and unstable output power caused by temperature fluctuations.

[0028] More preferably, the first detector, the second detector, and the third detector are all back-illuminated detectors; the first detector, the second detector, and the third detector are disposed on the coupler base, and the photodetector surfaces of the three detectors are respectively disposed on the three coupler output terminals. This structure is as follows... Figure 2 and Figure 3 As shown, each detector in detector assembly 6 is mounted on a coupler base. Specifically, the first, second, and third detectors are all InGaAs back-illuminated photodetectors. The coupler base is made of high thermal conductivity ceramic material, and its surface has positioning grooves that match the detector packages, ensuring precise alignment between the photodetector surfaces of the three detectors and the output terminals of the three couplers. This design eliminates the need for a gap between the detectors and the waveguide coupler 4, further reducing the device size.

[0029] In another implementation, the first, second, and third detectors are all front-illuminated detectors; the first, second, and third detectors are disposed on the substrate 10, and the photodetector surfaces of the three detectors are respectively opposite to the output terminals of the three couplers. The front-illuminated detectors in this solution have the advantages of convenient installation and low cost.

[0030] Furthermore, such as Figure 4As shown in the diagram, in the waveguide coupler 4: the first branch 1a of the first coupler shares the same optical transmission channel as the first output end of the beam splitter 41; the first branch 2a of the second coupler shares the same optical transmission channel as the second output end of the beam splitter 41. The beam splitter 41 receives the focused signal light and outputs the split signal light through three paths 1a, 2a, and 3a in the diagram (shown by solid arrows). The transceiver ends of the three couplers transmit the split signal light to the corresponding fiber optic sensing loops. The signal light returned from the fiber optic sensing loops (shown by dashed arrows) enters the transceiver ends of the three couplers respectively, and is finally output through the three branches 1b, 2b, and 3b in the diagram, and is detected by the corresponding detectors. The waveguide coupler 4 in this application makes reasonable use of a common optical path for the transmission of the round-trip signal light, further reducing the size of the device.

[0031] In this embodiment of the application, the lithium niobate Y-waveguide modulator group 8, such as Figure 2 and Figure 3 As shown, the first, second, and third lithium niobate Y-waveguide modulators are independently configured. This further reduces electrical crosstalk. More preferably, each lithium niobate Y-waveguide modulator in the lithium niobate Y-waveguide modulator group 8 is arranged in a direction perpendicular to the substrate 10. The lithium niobate Y-waveguide modulator is a key component in fiber optic gyroscope systems, such as... Figure 5 As shown, the lithium niobate Y-waveguide modulator includes a waveguide 81 and a modulation electrode 83. The light beam is split by an optical beam splitter 82 and enters both ends of the fiber optic sensitive loop. The lithium niobate Y-waveguide modulator can realize functions such as optical signal polarization, beam splitting, and modulation. Compared with the design of a planar structure for the three-way lithium niobate Y-waveguide modulator, this embodiment adopts a vertically coupled packaging method to isolate the horizontal electro-optic modulation of the three Y-waveguides, effectively reducing channel crosstalk; at the same time, the length is shortened, which is beneficial to the miniaturization of the entire device.

[0032] In some preferred solutions, such as Figure 3As shown, the low-electrical-crosstalk triaxial integrated fiber optic gyroscope further includes an isolation cavity 7, which is disposed above the waveguide coupler 4. The circuit board 5 is disposed within the cavity of the isolation cavity 7. Each detector in the detector group 6 is electrically connected to the signal processing circuit on the circuit board 5 via a wire 61. In specific applications, active devices such as the laser chip 1, the cooler 2, the circuit board 5, and the modulation electrode 83 of the lithium niobate Y-waveguide modulator are encapsulated in a single housing. Undesirable electrical crosstalk may be introduced between different signals. Since the signals received and processed by the detectors are weak, electrical crosstalk has a significant impact on them, leading to changes in the zero bias value of the fiber optic gyroscope. In this embodiment, to reduce the impact of interference signals on the detector output signal, the circuit board 5 is placed in the isolation cavity 7, thus isolating the signal processing circuit from other electrical components. Preferably, the isolation cavity 7 is made of a magnetic shielding material, which includes metal, to achieve physical isolation and absorption of electromagnetic signals. The design of isolation cavity 7 can reduce the influence of the modulation signals of cooler 2 and lithium niobate Y waveguide modulator on the output signal, and improve the zero-bias stability of the fiber optic gyroscope output.

[0033] This application also provides a fiber optic gyroscope, including the low-electrical-crosstalk (LEC) three-axis integrated fiber optic gyroscope integrated device described in the above embodiments. This fiber optic gyroscope, employing a LEC three-axis integrated fiber optic gyroscope structure, realizes functions such as optical signal splitting, transmission and reception, and modulation. All the functions of a three-axis fiber optic gyroscope can be achieved simply by fusing the polarization-maintaining fiber to the fiber optic sensing ring. It offers advantages such as low crosstalk, high integration, small size, and low cost. Furthermore, the fiber optic gyroscope provided in this embodiment, due to its hybrid integrated design, reduces assembly processes, material types, and labor costs, facilitating large-scale production and lowering the overall manufacturing cost of the module. Miniaturized, low-cost integrated modules can promote the penetration of fiber optic gyroscopes in consumer and industrial fields, expanding into new application scenarios (such as autonomous driving and the Internet of Things), making its applications more flexible and universal.

[0034] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0035] The above are merely the principles and preferred embodiments of this application. It should be noted that, for those skilled in the art, several other modifications can be made based on the principles of this application, and these modifications should also be considered within the scope of protection of this application.

Claims

1. A low-electrical-crosstalk triaxial integrated fiber optic gyroscope device, characterized in that, The package includes a housing, which comprises a substrate and a cover, wherein the substrate is provided with: Laser chips are used to emit signal light; The lens group, including a collimating lens and a focusing lens, is arranged along the propagation direction of the signal light to collimate and focus the signal light; A waveguide coupler includes a coupler base, and a 1-to-3 beam splitter, a first coupler, a second coupler, and a third coupler disposed on the coupler base. The input end of the 1-to-3 beam splitter receives focused signal light, and its first output end outputs split first signal light, its second output end outputs split second signal light, and its third output end outputs split third signal light. A first branch of the first coupler is connected to the first output end, its second branch serves as an output end, and its main branch serves as a first transceiver end. A first branch of the second coupler is connected to the second output end, its second branch serves as an output end, and its main branch serves as a second transceiver end. A first branch of the third coupler is connected to the third output end, its second branch serves as an output end, and its main branch serves as a third transceiver end. A lithium niobate Y-waveguide modulator group includes: a first lithium niobate Y-waveguide modulator, the signal end of which is connected to the first transceiver end, and the external end of which is connected to an optical fiber sensitive ring via a polarization-maintaining fiber; a second lithium niobate Y-waveguide modulator, the signal end of which is connected to the second transceiver end, and the external end of which is connected to an optical fiber sensitive ring via a polarization-maintaining fiber; and a third lithium niobate Y-waveguide modulator, the signal end of which is connected to the third transceiver end, and the external end of which is connected to an optical fiber sensitive ring via a polarization-maintaining fiber. The detector group includes: a first detector that detects the induced light signal at the output of a first coupler and processes it into a first electrical signal; a second detector that detects the induced light signal at the output of a second coupler and processes it into a second electrical signal; and a third detector that detects the induced light signal at the output of a third coupler and processes it into a third electrical signal. The circuit board has a signal processing circuit on it, which receives and analyzes the first electrical signal, the second electrical signal and the third electrical signal transmitted by the detector group.

2. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 1, characterized in that, Also includes: A cooler, located at the bottom of the laser chip, is used to control the temperature of the laser chip to remain within a set temperature range.

3. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 1, characterized in that: The first detector, the second detector, and the third detector are all back-illuminated detectors; The first detector, the second detector, and the third detector are disposed on the coupler base, and the light detection surfaces of the three detectors are respectively disposed on the three coupler output terminals.

4. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 1, characterized in that: The first detector, the second detector, and the third detector are all front-illuminated detectors; The first detector, the second detector, and the third detector are disposed on the substrate, and the photodetector surfaces of the three detectors are respectively opposite to the output terminals of the three couplers.

5. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 1, characterized in that, In the waveguide coupler: The first branch of the first coupler shares the same optical transmission channel with the first output terminal of the splitter. The first branch of the second coupler shares the same optical transmission channel as the second output of the splitter.

6. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 5, characterized in that, In the lithium niobate Y-waveguide modulator group: The first lithium niobate Y-waveguide modulator, the second lithium niobate Y-waveguide modulator, and the third lithium niobate Y-waveguide modulator are set up independently.

7. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 6, characterized in that: Each lithium niobate Y-waveguide modulator in the lithium niobate Y-waveguide modulator group is arranged in a direction perpendicular to the substrate.

8. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to any one of claims 1-7, characterized in that, Also includes: An isolation cavity is provided above the waveguide coupler, and the circuit board is disposed within the cavity of the isolation cavity; Each detector in the detector group is electrically connected to the signal processing circuit on the circuit board via a wire.

9. The low electrical crosstalk triaxial integrated fiber optic gyroscope device according to claim 8, characterized in that: The isolation cavity is made of magnetic shielding material, which includes metal.

10. A fiber optic gyroscope, characterized in that, Includes the low electrical crosstalk triaxial integrated fiber optic gyroscope device as described in any one of claims 1-9.

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