Research on Dynamic Grating Cascaded Fiber Bragg Grating Fabry-Perot Cavity

With the development of optical fiber technology, the application of dynamic grating has been widely concerned, such as optical fiber sensor, tunable narrow-band filter, fiber amplifier and so on. The erbium-doped fiber is selected as the dynamic grating, and one end of the erbium-doped fiber is connected. The forward wave is reflected by the Fiber Bragg Grating (FBG) to form a backward wave propagating backward. If the reflectivity of the Bragg grating is very close to 1, the standing wave field formed by the forward wave and the backward wave is perfect standing wave. The transmittance is calculated by the transmission matrix, and the grating parameters are converted into the control parameters in the writing process by the program-aided design, so as to guide the writing of the fiber grating. An important property of Fabry-Perot cavity is that its output spectrum can be dynamically modulated by adjusting parameters. Due to the adjustable parameters of the erbium-doped dynamic grating, compared with Fabry-Perot cavity composed of two identical fiber gratings, the parameters can be flexibly adjusted, and the fiber Bragg gratings at both ends of Fabry-Perot cavity can be fully symmetrical, which theoretically guarantees the optical performance 100% lossless transmission is conducive to the mode selection of Fabry-Perot cavity. The optical fiber Fabry-Perot cavity can be applied to the optical signal processing of optical fiber communication or the field of optical fiber sensing.