Theoretical Analysis And Investigation Of The Photonic Crystal Fiber For Fiber Optic Gyroscope Application

Since the first photonic crystal fiber (PCF) was emerged in 1996, due to its special optical properties, it received abroad attention. Compared with normal optical fiber, PCF has characteristics of low bending loss, great dispersion, lower sensitivity of temperature and stress. At the same time, it has degree of design, it can achieve high mode birefringence by changing the size of air holes or air-hole pitch and other parameters. Therefore, the development of photonic crystal fiber and application provides a broad prospect of research for the fiber optic gyroscope (FOG).Firstly, this paper summarized the development of PCF and FOG respectively, and analyzed the application of PCF in FOG. Then, the basic concepts and analysis procedures of finite element method (FEM) were introduced, and the numerical analysis method of photonic crystal fiber based on FEM was detailed derivation.Secondly, a new total internal reflection photonic crystal fiber (TIR-PCF) structure-quinquangular-core photonic crystal fiber (Q-PCF) was proposed. The effective index, modal field profile and dispersion properties of the standard hexagonal photonic crystal fiber (H-PCF) and the new PCF were investigated and compared by using a full-vector finite method. Considering the effect on the fiber loss from the limited capacity to the mode field by fiber, the structure of this new PCF was optimized and improved.Thirdly, the shortage of the traditional single-mode fiber and polarization maintaining fiber which used in the FOG was introduced and analyzed. However, these problems just can be solved by using photonic crystal fiber. In view of the requirements of polarization maintaining which in the application of the FOG, a new kind of highly birefringent photonic crystal fibers structure was proposed by changing the size of some air-hole which near the fiber core. The effective index, modal field profile and birefringence properties of the standard highly birefringent hexagonal photonic crystal fiber and the new highly birefringent PCF were investigated and compared. Because the excellent birefringence and mode field characteristics, The new highly birefringent PCF can well saitisfy the application of real optical sensing systems which need high polarization and reliability, e.g. fiber optic gyroscope.Finally, the present situation of photonic crystal fiber optic gyroscope was presented. A scheme of an interferometric fiber optic gyroscope (I-FOG) was established with the new designed highly birefringent PCF. And the theoretical model of this I-FOG was established, which is the theoretical basis for the actual application.