Analysis And Suppression Method Of Resonant Microoptical Gyroscope Noise

Resonant optical gyroscopes have been widely used in civil,military,aerospace and other fields,ranging from automobiles and drones to airplanes,ships,rockets,missiles,satellites,and more.The high-precision angular velocity sensor based on the Sagnac effect resonant microoptical gyroscope(RMOG)is rapidly developing due to its advantages of integration,miniaturization,low power consumption,and high accuracy.It has gradually become one of the hot research topics at home and abroad.However,currently,the frequency difference signal generated by resonant micro-optical gyroscopes based on the optical Sagnac effect theory is relatively weak,and various reciprocal and non-reciprocal noise are introduced in the optical path and circuit.The suppression schemes for various types of noise are not yet perfect,which will greatly reduce the output accuracy of the gyroscope rotation signal.Therefore,it is crucial to propose a solution for suppressing gyroscope optical noise and signal locking to solve gyroscope noise.This article mainly focuses on the processing of optical noise in gyroscope systems.By using digital detection locking,digital filtering and other techniques to suppress optical backscatter noise and Kerr noise,the signal-to-noise ratio of the gyroscope system is improved,thereby improving the digital detection accuracy and ultimately improving the angular velocity output accuracy of the gyroscope.The system uses a silicon dioxide waveguide resonant cavity as the sensitive component,combined with a detection system centered on FPGA chips to suppress reciprocal and non-reciprocal noise.The laser frequency locking technology and digital system weak signal detection technology are designed and optimized,and a resonant micro-optical gyroscope closed-loop detection system is built.Based on this,dynamic and static tests of the gyroscope are carried out,and the performance indicators of the gyroscope system are finally obtained.The specific experimental content and work conclusions are as follows:(1)In terms of backscattering noise suppression,this article analyzes the main sources of Rayleigh backscattering noise in RMOG and its interference to the system.Two types of backscattering noise elimination methods are analyzed through theory.Finally,an optical path is constructed on this basis,and the half wave voltage and maximum carrier suppression ratio of dual modulation are measured.A single-phase sine wave was loaded onto a lithium niobate phase modulator,and the influence of the first type of backscattering noise on the resonance curve trough and demodulation curve resonance point in the gyroscope system was tested by changing the modulation frequency.The optimal modulation frequency was obtained.Through the scheme of spectrum separation,it has been proven that the carrier suppression ratio of the phase modulator can be superimposed under the scheme of applying dual-phase signal modulation.Through experiments,it has been shown that under dual phase sine wave modulation,the backscattering noise has been reduced from 6.03 m V to 0.59 m V,and the zero bias stability value of the gyroscope system has been reduced from 97.14 °/h to 9.76 °/h.The overall suppression effect has been improved by an order of magnitude,and the backscattering noise has been effectively suppressed.(2)Theoretical analysis was conducted on the causes of Kerr noise,and Kerr noise testing was conducted on a dual loop resonant micro-optical gyroscope.Design a 0 light intensity feedback loop based on the intensity modulator,and transmit real-time data through a photodetector and FPGA to accurately measure the optical power of the optical path.The FPGA loads the feedback in the form of high-precision voltage into the intensity modulator,thereby improving the stability of the two optical power paths.The final experimental test showed that the power fluctuation difference between the two optical channels decreased from 7.4m V to0.79 m V,and the zero deviation of the gyroscope system decreased from 9.76 °/h to 0.98 °/h,which increased by an order of magnitude.(3)Completed the construction of the RMOG system and tested it,mainly including module testing and system testing.The module testing mainly includes modulation and demodulation module,servo control module,and optical feedback circuit testing.System testing includes backscatter noise testing,Kerr noise testing,as well as dynamic and static testing of gyroscopes.The final use of Allan variance calculation resulted in an hourly zero deviation of RMOG of 0.98 °/h.