Design And Implementation Of Signal Detection System For Photonic Crystal Fiber Optic Gyroscope

Fiber optic gyroscope(FOG)is an inertial navigation instrument which can be used for navigation,guidance,and so on.There are many advantages of all solid state,such as shock resistance,low cost and wide detection range.Resonator fiber optic gyro(R-FOG)is the second generation of fog.As same as the principle of all optical gyroscope,R-FOG is based on the Sagnac effect.The angular velocity can be obtained by the difference of the resonant frequency of ring resonator clockwise and counterclockwise optical path.The weak signal frequency difference can be extracted by coherent detection principle which apply lock-in amplifier.In this way,the system can reduce the new reciprocity noise by the components of fiber optic gyro,because the laser and resonant cavity are easily disturbed by temperature ? stress and another environmental factors changing.In order to keep the linear output of R-FOG,the laser center frequency need follow the resonant frequency of the resonant cavity,the output frequency of light road is always maintained at the resonant state.The other light road is used for the output by detecting the difference between the resonance frequency and the center frequency of the laser.Based on the above research background,from the principle of R-FOG detection begin to the reserch,combined with the scheme of photonic crystal fiber instead of the ordinary polarization maintaining fiber,the resonant photonic crystal fiber(RPCFOG)signal detection system is established.Specific research work carried out:First of all,the conventional polarization maintaining fiber ring resonator is replaced by photonic crystal fiber resonator to improve the environmental effect based.Combining the Sagnac effect,research analysis of resonant cavity on the in-depth and expounds the influence of different parameters on the resonant characteristics,which including the effects of narrow linewidth laser for clarity.On the basis of the above work,the closed-loop detection system of resonator photonic crystal fiber gyroscope is established.Then,on the basis of the sinusoidal phase modulation,phase-locked amplifier is designed to establish an analog demodulation scheme.Based on the design software and simulation software of filter,the system uses second-order Sallen_Key type low-pass filter that is differ from general first-order back-end filter demodulation to improve the filtering effect,and completes the synchronous demodulation of the signal.On the basis of the above work,lock frequency of digital PI control algorithm is established by FPGA as the core of the hardware unit.The system uses incremental form of digital implementation,based on the analysis of Proportion,Integration link to the system,under the influence of combined with the simulation of control parameter setting.Then,from the perspective of hardware system overall analysis of performance and application of FPGA,design selects the suitable FPGA chip,the high performance of signal modulus to A/D or D/A conversion,and FPGA serial port communication with the PC,which can enhance the system's usability and flexibility.Finally,this paper designs a test system to complete the testing and verification of each module of the resonator fiber optic gyro detection system.The design and implementation of the detection system for the resonant photonic crystal fiber optic gyro(FOG)can establish a good foundation for the future application of the resonator fiber optic gyro.