Fiber-optic gyroscope scale factor stabilizing device and method based on integrated optics chip

Abstract

This invention discloses a scaling factor stabilization device and method for fiber optic gyroscopes based on an integrated optical chip. The device includes a highly integrated optical chip and a fiber optic interferometer, fused together via polarization-maintaining fiber. The optical chip integrates a 1310nm SLD light source, a same-wavelength optical filter, a 1:1 beam splitter unit, and two InGaAs photodetectors on the same substrate. This invention uses the detectors within the optical chip to monitor the power changes of the light source's output in real time, and uses this feedback to control the light source's operating state, thereby actively stabilizing its center wavelength. This effectively improves the gyroscope's stability in environments with varying temperatures. Simultaneously, the integrated design greatly simplifies the optical path structure, reduces assembly difficulty, and facilitates the miniaturization of fiber optic gyroscopes.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing and inertial navigation technology, specifically to an optical chip device and method for fiber optic gyroscopes that can actively stabilize the scaling factor and achieve high integration. Background Technology

[0002] Fiber optic gyroscopes (FOGs) are core inertial sensors that measure rotational angular velocity based on the Sagnac effect. The scale factor (SF) of their output signal is inversely proportional to the center wavelength of the light source. Superluminescent diodes (SLDs), due to their wide spectrum and low coherence, effectively suppress backscattering and coherent noise, have become the preferred light source for fiber optic gyroscopes. However, the output center wavelength and power of SLD light sources drift significantly with ambient temperature and their own drive current, causing changes in the gyroscope's scale factor.

[0003] To improve stability, existing technologies typically employ two approaches: one is to precisely control the temperature of the SLD light source, but this cannot fully compensate for wavelength drift caused by current; the other is to use discrete optical components (such as additional Fabry-Perot etalons and detectors) to build an external wavelength monitoring system, compensating through feedback. While these solutions have some effectiveness, they result in bulky systems, complex optical path structures, and difficult assembly and debugging. Furthermore, multiple fiber optic interfaces introduce additional polarization fluctuations and losses, making it difficult to meet the urgent demands of modern inertial navigation systems for high precision, miniaturization, and high reliability.

[0004] Therefore, there is an urgent need for a solution that can achieve in-situ, real-time monitoring and control from the light source and has a high degree of integration, so as to fundamentally stabilize the scaling factor performance of fiber optic gyroscopes. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provide a fiber optic gyroscope scaling factor stabilization device and method based on an integrated optical chip. Its core is to internalize light source stabilization and signal detection functions through a multi-functional integrated chip design, thereby improving performance while achieving miniaturization, high reliability, and low loss in the device.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A fiber optic gyroscope scaling factor stabilization integrated optical chip, characterized in that it comprises: a semiconductor broadband light source; an optical filter disposed on the output optical path of the semiconductor broadband light source; an optical beam splitter disposed on the output optical path of the optical filter, for splitting the filtered light into a first optical path and a second optical path with an optical power ratio of 1:1; a first photodetector for receiving the optical signal of the first optical path; and a second photodetector for receiving the return optical signal from an external Sagnac interferometer; wherein all components are integrated on the same substrate.

[0007] A fiber optic gyroscope scaling factor stabilization device incorporating the aforementioned chip further includes: a Sagnac interferometer, comprising a multifunctional integrated optical chip and a sensing fiber optic ring; and a signal processing and control circuit. The second optical path output of the integrated optical chip is connected to the input of the Sagnac interferometer via a polarization-maintaining fiber, and the output of the Sagnac interferometer is connected back to the second photodetector input of the integrated optical chip via a polarization-maintaining fiber. The signal processing and control circuit is electrically connected to the first and second photodetectors and the semiconductor broadband light source, respectively.

[0008] A scaling factor stabilization method using the above-mentioned device is characterized by the following steps: S1: The light emitted by the semiconductor broadband light source is filtered by an optical filter and then split into two beams at a 1:1 ratio by an optical beam splitting unit. S2: The first beam is received by a first photodetector, and its output signal is sent to a signal processing and control circuit to generate a feedback control signal to adjust the light source drive current and stabilize the output power of the light source. S3: The second beam, as a probe beam, is output from the chip and injected into the Sagnac interferometer via a polarization-maintaining fiber. The interference signal light output by the interferometer returns through the polarization-maintaining fiber and couples to the second photodetector on the chip. S4: The signal processing and control circuit processes the signal from the second photodetector and calculates the rotational angular velocity.

[0009] This invention achieves a dual closed-loop system through the above design: a power stabilization loop for the light source formed by the first detector, and a Sagnac interferometer signal detection loop formed by the second detector. Both are integrated into a single chip. A 1:1 splitting ratio is used, ensuring that the monitoring branch obtains an optical signal to improve control accuracy, while the main sensing optical path retains sufficient energy, achieving an optimal balance between monitoring accuracy and sensing performance. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall device structure according to an embodiment of the present invention.

[0011] Figure 2 for Figure 1 A planar optical path layout diagram of an embodiment of an integrated optical chip (100).

[0012] Figure 3 This is a block diagram illustrating the control logic of the present invention.

[0013] Numbering on the map: 100-Integrated Optical Chip 101-Semiconductor Broadband Light Source (SLD) 102-Optical Filter 103-Optical beam splitter unit (1:1) 104 - First photodetector (PD1) 105 - Second photodetector (PD2) 106-Output / Input Port 200-Signal Processing and Control Circuits 300-Multifunctional Integrated Optical Chip (Y-waveguide) 400-Sensing Fiber Optic Ring Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment uses a silicon-based optoelectronic integration platform as an example, but this does not constitute a limitation on the scope of protection of this invention.

[0015] Example: A fully integrated optical chip and gyroscope device employing 1:1 beam splitting refer to Figure 1 and Figure 2 This embodiment provides a fully integrated fiber optic gyroscope optical chip 100 and a gyroscope device containing the same.

[0016] Chip Structure: A silicon-on-insulator (SOI) wafer is used as the common substrate. A silicon optical waveguide is fabricated on the chip using semiconductor processes. A silicon light-emitting diode (SLD) chip 101 with a center wavelength of 1310 nm is integrated into the end-coupling region of the chip using a high-precision flip-chip bonding process. A small dielectric thin-film interference filter 102 with a center wavelength of 1310 nm is integrated on the output waveguide of the SLD for spectral shaping. Downstream of the filter is a 1x2 optical beam splitter unit 103, designed with a precise 1:1 splitting ratio.

[0017] One output arm (50% optical power) of beam splitter 103 is directly coupled to an InGaAs photodiode 104 (PD1) to form a power monitoring branch. The other output arm (50% optical power) of beam splitter 103 is connected to a low-loss grating coupler 106 at the chip edge as a system optical output / input port. The input of another InGaAs photodiode 105 (PD2) is also connected via a waveguide to a grating coupler for receiving return light.

[0018] System Connection: The output port 106 of chip 100 is fused to the input of a commercially available multifunctional integrated optical chip 300 (Y-waveguide) via a polarization-maintaining fiber. The two outputs of the Y-waveguide 300 are connected to a polarization-maintaining sensing fiber loop 400, forming a Sagnac interferometer. The interference signal light from one of the outputs of the Y-waveguide 300 is back-coupled to the input port on chip 100, specifically designed for PD2 105, via another section of polarization-maintaining fiber.

[0019] Working principle (in combination) Figure 3 ): Light source amplitude stabilization loop: The light emitted by SLD 101 is shaped by filter 102 and then evenly split by 1:1 beam splitter 103. One beam (50%) is received by PD1 104. The signal processing and control circuit 200 reads the current value I1 of PD1 and compares it with a highly stable DC reference voltage V_ref (corresponding to the target optical power). The resulting error signal is processed by the PID controller, which outputs a control voltage to dynamically adjust the drive current of SLD 101, thereby locking the output optical power of SLD at a constant value. Due to the use of 1:1 beam splitting, the monitored branch optical power is sufficient, significantly improving the accuracy and stability of the control loop.

[0020] Sagnac Interferometer and Probe Loop: Another main beam (50%), after amplitude stabilization, is output from the chip and enters the fiber loop 400 via the Y-waveguide 300. When the system rotates, a Sagnac phase shift is generated, which, after modulation, is output by the interferometer as a modulated optical signal. This signal returns to the chip and is received by PD2 105. The signal processing and control circuit 200 demodulates the output signal I2 of PD2, thus accurately calculating the rotational angular velocity Ω.

Claims

1. An integrated optical chip for fiber-optic gyroscope scale factor stabilization, characterized by, include: A semiconductor broadband light source; an optical filter disposed in the outgoing light path of the semiconductor broadband light source; An optical beam splitter is disposed on the output optical path of the optical filter and is used to split the filtered light into a first optical path and a second optical path with an optical power ratio of 1:1; a first photodetector is used to receive the optical signal of the first optical path; The second photodetector is used to receive the returned optical signal from the external Sagnac interferometer; wherein the semiconductor broadband light source, optical filter, optical beam splitter, first photodetector and second photodetector are integrated on the same substrate.

2. The integrated optical chip according to claim 1, characterized in that, The semiconductor broadband light source is a superluminescent diode with a center wavelength of 1310 nm.

3. The integrated optical chip according to claim 1, characterized in that, The optical filter is a dielectric thin-film filter or an integrated waveguide grating with a center wavelength of 1310nm.

4. The integrated optical chip according to claim 1, characterized in that, It also includes a first signal processing unit, which processes the output signal of the first photodetector and compares it with a preset power reference value to generate a feedback signal to adjust the driving current of the semiconductor broadband light source, thereby stabilizing its output optical power.

5. A fiber optic gyroscope scaling factor stabilization device, characterized in that, include: The integrated optical chip as described in any one of claims 1 to 4; the Sagnac interferometer, comprising a multifunctional integrated optical chip and a sensing fiber optic ring; a signal processing and control circuit; wherein, the second optical path output terminal of the integrated optical chip is connected to the input terminal of the Sagnac interferometer via a polarization-maintaining fiber, and the output terminal of the Sagnac interferometer is connected to the input terminal of the second photodetector of the integrated optical chip via a polarization-maintaining fiber; the signal processing and control circuit is electrically connected to the first photodetector, the second photodetector, and the semiconductor broadband light source, respectively.

6. A method for stabilizing the scaling factor of a fiber optic gyroscope using the device described in claim 5, characterized in that, The process includes the following steps: the light emitted by the semiconductor broadband light source is filtered by an on-chip optical filter and then split into a first beam and a second beam by a beam splitter unit at a 1:1 ratio; the first beam is received by a first photodetector, and its output signal is processed and used to control the operating parameters of the semiconductor broadband light source to stabilize the output characteristics of the light source; the second beam is output from the chip, injected into a Sagnac interferometer via a polarization-maintaining fiber, and the resulting interference signal light returns via the polarization-maintaining fiber and is received by the second photodetector; the output signal of the second photodetector is processed to calculate the rotational angular velocity.

7. The method according to claim 6, characterized in that, The operating parameter is the driving current of the semiconductor broadband light source.

8. A fiber optic gyroscope, characterized in that, It includes the fiber optic gyroscope scaling factor stabilization device as described in claim 5.

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