Study On Nonlinearity And Negative Refraction Of Photonic Crystal Fibres

Photonic crystal fiber is a new kind of fiber. Comparing with traditional fiber, it has many unusual properties including nonlinear properties. Dielectric media with negative index of refraction, as a new kind of artificial electromagnetic media, has attracted great interest in recent years. The original jobs in research are listed as follow:1. Research the effect of different structure parameters on the nonlinearity coefficient of photonic crystal fiber (PCF) with hexagonal shape. Here, the fiber core of photonic crystal fiber with hexagonal shape is solid. Using the effective refraction method, PCF of which background material are negative and positive is discussed. The result is whatever the refractive index of background materials is negative or positive, the nonlinearity coefficient will increase if d increases or A decreases. There is something different that negative nonlinearity coefficient will occur when the refractive index of background materials is negative.2. Research on the nonlinearity coefficient of photonic crystal fiber with air fiber core. The result is whatever the refractive index of background materials is negative or positive, the nonlinearity coefficient can obtain the max> mix and negative number.3. The optical gain of doped same axis photonic crystal fiber with active or high refractive index impurity is studied by the transmission matrix method. The result is that the index of transmitting is greater than one owing to amplification of stimulated emission, and some narrower gain transmission bands are obtained.4. Transmission spectrum from triangular structure PCs with equivalent negative index of refraction is studied with finite difference time domain (FDTD) method. If selecting the correct frequency, the negative or positive transmittance peak can be obtained. So the unilateral light transmitting can formed. The conclusion provides the theory basis to the negative or positive unilateral optical switching with high-Q.All regulations provide the theory basis to photonic crystal fiber applying in optic dense wavelength division multiplexed (DWDM) optical communications.