Short Fiber Resonant Optic Gyroscope Using The Pound-Drever-Hall Technique

Resonant micro-optic gyroscope(RMOG),whose core sensing element is the waveguide ring resonator with a total length of from several centimeters to tens of centimeters,has obvious advantages in miniaturization and integration.Due to the limitation of the current low loss optic waveguide materials and manufacturing process,the short fiber ring resonator is used as the core sensing element,and the high-frequency Pound-Drever-Hall(PDH)technique is applied to gyroscope for signal modulation and demodulation.This dissertation researches on the optic gyroscope with s short fiber ring resonator as the core sensing element.Specifically,the main contents are as follows:(1)Design and develop two kinds of optic fiber resonator with the total length of 30cm and 60cm respectively.The finesse of the short fiber ring resonator with the total length of 30cm and the diameter of 4.77cm(2 circles)is up to 1324.In the short fiber ring resonator with the total length of 60cm and the diameter of 4.77cm(4 circles),the power of secondary eigenstate of polarization is smaller and the finesse is 145.6.For the resonant optic gyroscope with the core sensing element of short fiber ring resonator,when the average optical intensity detected by the photodetector is assumed to be lmW,the theoretical resolution is 0.33°/h.(2)Use the high-frequency PDH technique for signal detection in the resonant optic gyroscope with the core sensing element of a short fiber ring resonator.Aiming at maximizing the slope of demodulation curve and suppressing the laser frequency noise effectively,the PDH technique theory is realized.Combined with the actual short fiber ring resonator structure and FPGA digital signal processing platform,the modulation index and frequency are optimized.Experiment results show that,compared with the low frequency modulation and demodulation technique,the high-frequency PDH technique increases the slope of the demodulation curve by a factor of 1.23,which is 1.27 theoretically.Establish the laser frequency noise power spectral density(PSD)measurement system based on Mach-Zehnder Interferometer(MZI).The test results show that in the resonant optic gyroscope applied with the traditional low frequency,the laser frequency noise within the range of DC-2kHz is inhibited.When the high-frequency PDH technique is applied,the laser frequency noise is reduced significantly up to 6 kHz,and the ability for noise suppression has been greatly improved.(3)Build the resonant optic gyroscope experimental system,which uses the short fiber ring resonator with the total length of 60cm and the diameter of 4.77cm,and the optimized high-frequency PDH technique is applied for signal modulation and demodulation.The test results show that,compared with the low frequency modulation and demodulation technique,when the high-frequency PDH technique is used,the locking precision of the resonant frequency servo loop is improved to 0.26°/h from 4.32°/h.The minimum of Allan deviation of the resonant optic gyroscope increases from 9.6°/h to 8°/h during 1 hour of test time.