Achievement of a Tunable Filter Based on the Fiber Fabry-Perot Interferometer and Fiber Bragg Gratings

In this paper, we demonstrate a method about designing a tunable and multiple-channel filter. The filter is a combination of a fiber Fabry-Perot interferometer (FPI) and fiber Bragg gratings (FBGs). Through utilizing different period fiber gratings, we can attain a larger free spectral range, and keep the FWHM small in the meantime, so over 30 nm of free spectral range and 0.058 nm of FWHM of this filter are achieved.