Tunable Chirped Fiber Bragg Grating Filter Based on Special Strain Function Modulation and Its Application in Fiber Sensor

A novel technique for chirp control of a uniform fiber Bragg grating (FBG) based on the special strain function modulation is presented. A cylinder taper cantilever beam (CTCB) is specially designed and capable of providing special position-dependent strain function gradients along an originally uniform FBG, which allows tunable quasi-triangular and quasi-Gauss-gradient FBG filter. Furthermore, the feasibility of the tunable chirped FBG based on the strain function modulation as sensor is validated. This state-of-art technique is expected to be applied in fiber filter, FBG sensor and multiwavelength fiber laser.