Research In The Physical Features Of Adjustable Micro-Strured Fiber Bragg Grating

With the special air hole structure, the microstructure fiber has a strong adjustability. On the one hand it can be provided with a particular optical property by structure design, on the other hand it also gain improved or enhanced properties by the way of material filling. Because of the micro-holes structure, the fiber Bragg grating based on microstructure fiber has a number of superior properties to the general grating. so it is of great importance to study in this grating. At present, the researches on it mainly focus on the structure design and the way of grating writing, witch determines the spectral features. But there are no reports about the research on the microstructure fiber Bragg grating with material filling.The structural feature of microstructure fiber is discussed in this paper, and with the finite element method and the couple-mode theory, it is analyzed that the reflection wavelength of microstructure fiber Bragg grating at different refractive index in the air holes, the temperature sensing properties of microstructure fiber Bragg grating with material filling , the influence on the reflection spectrum of microstructure fiber Bragg grating with multi-peaks by structural parameters and refractive index in the air holes, and the temperature sensing properties of the fiber Bragg grating based on the helix liquid crystal in the core air column of the hollow core microstructure fiber. For the microstructure fiber Bragg grating with material filling, the study shows that the reflective peaks shift to the longer wavelength with the increase of the material refractive index, and shift faster and faster. For the microstructure fiber Bragg grating with material filling sensitive to temperature, it is more sensitive to the air filing greatly. And for the microstructure fiber Bragg grating with material filling and multi-peaks, with the increase of the refractive index of the material filled in the air holes, the resonant wavelength of the core mode have no any change while the resonant wavelength of the cladding modes have a great shift to the long wavelength. For the microstructure fiber liquid crystal grating, the results show that to the pitch the typical liquid crystal which increases with temperature increment, the resonant wave length red shift, band width reduces, time delay increases, the normalized frequency reduces, the boundary of single model and multi-mold approaches to the multi-mold of microstructure fiber liquid crystal grating. The research findings in this paper could give important reference for the further research and design on new type sensors, adjustable reflector and other optical devices.