Solc-Like Tunable Birefringent Fiber Filter Based on Elliptical-Core Spun Fiber

A novel tunable all-fiber birefringent filter based on elliptical-core spun fiber (ECSF) is presented. It is the first time to build a discrete model of spun fiber by using Jones matrix analysis. The transmission characteristics of proposed filter are studied and discussed in detail, while a generalized formulation to express the transmissivity of the birefringent filter is derived. On this basis, the effect factors of filter characteristic are deeply analyzed and simulated. Compared with the conventional fiber-optic Solc filter, the proposal is easy fabricated and implemented with low loss. By utilizing appropriate length and parameters of the ECSF, a narrowband and high-extinction ratio periodic optical filter is realized. The proposed filter also can be finely tuned covering one free spectral range, which has potential applications for fiber sensing and flexible multi-wavelength fiber laser.