Study On The Coupling And Temperature Sensing Characteristics Of Dual-core Photonic Crystal Fibers

When light transmits in dual core photonic crystal fibers, there will be exchange of the power between two cores. In this dissertation, the coupling characteristics of dual cores and temperature sensing in photonic crystal fibers and its applications in novel designs of fiber couplers, splitters, wavelength selectors and sensors are discussed.We propose a new type of ellipse-shape hybrid dual core photonic crystal fiber simultaneously based on two guiding mechanisms of total internal reflection and photonic band-gap effects. We analyze the band-gap range, mode field distribution and effective refractive index. We apply the coupled-mode theory to analyze the coupling properties of the hybrid dual core photonic crystal fiber numerically and theoretically. We calculate the coupling length and analyze the effects of large air-hole diameter, the effective index of high effective index column, the high effective index of air-hole diameter and the pitch on the coupling length. By optimizing the structure parameters, we find the smallest coupling-length dual-core photonic crystal fiber, and analyze its birefringence, dispersion and other characteristics. Based on which, we also discuss its application in couplers, splitters and wavelength selectors.We also design a new type of all solid dual-core photonic band-gap crystal fiber with filling liquid, and study its coupling and temperature sensing. We find that the resonant mode in supermodel and high effective index column play important roles in coupling, and there will be a single extreme or more extreme values with high temperature, and the effective index of odd mode will jump with the temperature or the wavelength. Changing wavelength can make optical switch when the temperature is fixed, and changing temperature can make sensor when the wavelength is fixed.The results have important reference value on coupling characteristics and sensing characteristics for dual-core photonic crystal fibers and the relevant practical applications.