Characteristic Study Of All-solid Fiber Based On Linear Array Structure

Compared with the traditional optic fiber in which the guiding light mechanism is the total internal reflection,all-solid photonic crystal fiber is a glass of fiber which is based on the photonic band-gap effect mechanism. The core refractive index is less than the refractive index of cladding and the light will be bind in the fiber core when it spreads in that fiber.All-solid linear array structure fiber inherits the advantages of conventional photonic crystal fiber as well as its own unique advantages. In this paper, the characteristics of a linear array structure of all-solid fiber and its improved structure are numerically studied, including the mode field characteristics, constraints loss characteristics, bending characteristics. The main works are summarized as follows:1. The advantages and applications of photonic crystal fiber photonic crystal fiber are reviewed. Some numerical algorithms of photonic crystal fiber are outlined, and highlight the plane wave expansion (PWE) method and finite element method (FEM). These theories are the foundations for further study.2. The linear array structure of all-solid fiber is theoretically studied by using PWE method. We discussed the band gap properties and the impact of the parameters of the fiber on the band gap. The results shows that in this fiber the fundamental mode locates in the second band gap; when the refractive index difference of high refractive index rod and core increases or the filling ratio of high refractive index rod become larger, the band gap moves down, the band gap wavelength range of the fundamental mode shifts to the long wavelength direction.3. The FEM is used to study the mode field properties and analyze the confinement loss,bending loss and birefringence of the fiber. The numerical results indicate that in addition to the fundamental mode,the second-order-mode is still existed,so it is not a single-mode fiber;4. We propose three improved structure of the all-solid fiber, analyze its mode field characteristics. The results show that the core energy percentage in "*" shaped structure fiber is highest and can reach 92.7% when the wavelength is 1.7?m. Also we focused on the confinement loss and bending loss in "*" shaped structure fiber, and then the effects of fiber parameters on fiber characteristics were studied. Studies show that with increasing the refractive index difference of high refractive index rod and core the band gap structure will move to the long wavelength direction; as the space between the high refractive index rods increases, band gap structure also shifts to the long wavelength direction. The fundamental mode is closed to the edge of the band gap in these fibers.