The optical characteristic of Fabry-Perot cavity with chirped fiber gratings

A Fabry-Perot cavity with chirped fiber gratings(CFGs) has been proposed and experimental demonstrated We use an ordinary single-mode fiber manufacturing two CFGs with reflection center wavelength 1549.74 nm by ultraviolet irradiation methods of phase mask method, two chirp fiber gratings with the same parameters: the length of the grating region is 10 mm, reflectivity is 95%, and bandwidth is 2.72 nm, chirp rate of 2 nm/cm, 1, 3 and 5 cm of two CFGs spacing. The Fabry-Perot (FP) cavity is composed of two CFGs as reflection faces. When an optical signal is input into the resonant cavity, the wavelength within the bandwidth of the CFGs satisfies the resonance condition, so the resonance is formed within the bandwidth. The structure is analyzed theoretically and the relationship between resonance spectrum and parameters is discussed. Wavelength changes are monitored by a spectral analyzer in real time. The experimental results show that the tunable laser output can be realized in optical communication system by changing the structure and parameters of the resonator.