Beat Frequency Analysis And Fiber Ring Resonator Design For B-FOG

Fiber Optic Gyroscope (FOG) is a new angular rate sensor based on the Sagnac effect. Compared with the traditional mechanical gyroscope, FOG has the advantages of wide dynamic range, low cost, light weight, long life and high reliability. Brillouin fiber Optic Gyroscope (B-FOG), which is named the third generation of FOG, represents high precision and miniaturization trends of FOG. However, it is now in the theoretical stage. This paper firstly researches the basic issues of B-FOG, and puts forth a modified B-FOG test system, then Brillouin optical-fiber ring is conducted in depth. Based on the study, B-FOG fiber ring resonator is designed and verified in experiments. Finally, the factors affecting beat frequency and the lock-in phenomenon is analysed. In detail studies are as follows:First, the Brillouin Fiber Optic Gyroscope principle is analysed in depth. With the latest development of optoelectronic devices, a modified B-FOG implementation scheme is put forward. Compared with international programmes, the problems such as source frequency fluctuations, polarization state changes, and also lock-in effect can be satisfactorily resolved. As a result, it can impact on Brillouin Fiber Optic Gyroscope prototype development with guiding significance.Second, the light intensity of Brillouin fiber ring have been studied. With Taylor series and recursive methods, the relation among pump light intensity, intracavity circulating light intensity, the Stokes light intensity and transmitted intensity is analysed in detail. As a result, pumping threshold of various bands Stokes can be get, and in accordance reasonable B-FOG working point is setted with transmitted intensity. Under the guidance of this theory, Brillouin fiber ring experimental system is designed. Test shows that Stimulated Brillouin Scattering threshold value is 0.787mW, ring resonator FSR is 6.737MHz, and the finesse is more than 100. Finally, the B-FOG beat frequency stability factor is analysed. From the theoretical and experimental research, temperature impact on Brillouin frequency shift is 1.36 MHz/℃, the temperature change of 9.1℃will cause Stokes-mode hopping. The mechanism that Kerr effect bring on nonlinear gyro scale factor is discussed, and the integrated beat frequency formula is given. Against the beat frequency locking effect, an all-fiber programme based on frequency offset is studied to avoid the buffeting of large volume and high cost, and also does not need a push-pull phase modulation as complicated computing. Finally, the realization of this programme is discussed.