Research On The Transmission Characteristics Of High-birefringence Sagnac Loop Filter

With the fast development of optical communication and fiber sensor technology, optical filters have become one important optical component and have been widely used in many areas. For example, the narrow-band filter is one key component in the WDM and DWDM systems. Therefore, various optical filters have always been one hot research area in Optical Fiber Communications, even in Optoelectronics. The filter, which is based on one or more high birefringence (HiBi) fiber Sagnac loop mirror, has the advantages such as simple structure, low cost, low insertion loss, polarization independence, high flexibility and stable performance, so it has potential application in the fields of demodulation of fiber sensor, tunable Multiwavelength fiber laser and fiber filter of optical communication and attracted widespread attention.Based on the Jones Matrix Theory, the various theoretic reflective and transitive functions of the one-stage HBF Sagnac filter are obtained. In order to check the theory, the relation between the frequency response and the parameter of filter such as the couple coefficient of the OC, the rotation angles of the PC, the length and the beat length of the HBF is detailed studied through Simulation and Experiment. And then the characteristics of N-Stage Solc-Sagnac and Lyot-Sagnac loops are theoretically and numerically analyzed , and designs of filters with good performance are given.