Research On The Characteristic And Application Of Dual-ring Optical Micro-cavity And Photonic Crystal Fiber

Recently, optical microstructure has been widely applied in photonics design, fundamental physics, all-optical communication and other areas due to its unique structure and optical properties. Therefore a great number of scholars have paid attention to this domain.Two different kinds of photonics microstructure, dual-ring optical micro-cavity and photonic crystal fiber are discussed. The main points are including:1. Two types of dual-ring optical micro-cavity have been presented in this paper. One is called dual-ring optical micro-cavity coupled Mach-Zehnder interferometer (MZI). The coupling matrix method is employed to deduce the formulas of transmittance and phase shift. Also, the coupled resonator-induced transparency (CRIT)and absorption (CRIA)have been researched. The other is a dual-ring optical micro-cavity reflector. The research of the response spectrum has been expressed by applying transfer matrix method to derive the formulas of transmittance and group delay. In this system, the center wavelength and the group delay of reflected signal are flexible controlled. Due to these characteristics, this system can replace the fiber brag grating to be the end-mirror of tunable laser or the reflector of filter.2. An absorption spectroscopy gas sensor based on HC-1550-02hollow-core photonic crystal fiber (HC-PCF) has been expressed. By simulating the mode field distribution of HC-1550-02PCF, the relative sensitivity could be calculated as0.96. It is significant for improving of the sensitivity of sensing system. Also, the progress of acetylene gas diffusion into the holes of HC-PCF has been theoretically and experimentally simulated. Moreover, the trends of experimental curves go very well with the theoretical simulation result. It shows that the time required for gas to diffusion into the hole can be shortened by introducing the pressure difference between the inside and outside of the gas cell. Then via setup the experimental system, the transmission spectrums of acetylene and ammonia could be obtained. Meanwhile an acetylene detective sensitivity of82ppmv could be calculated at1531.58nm.3. Based on two-level system rate equations of Er-doped fiber laser, the effect of nonlinear characteristic and mode competition to the sensitivity of sensing system around threshold has been analyzed. Then a dual-wavelength Er-doped fiber laser is setup, a variable attenuator rather than the gas cell is placed in the cavity to prove it. Moreover, in this system, a sensitivity enhancement factor of158.5is obtained. This enhancement mechanism has immense potential in high sensitivity intra-cavity absorption gas detection system.