Phase characteristics of fiber Bragg gratings and fiber Fabry-Perot cavities

Phase spectra of fiber Bragg gratings (FBGs) have significant impacts on spectral characteristics of FBG based Fabry-Perot (F-P) cavities. A concise and comprehensible expression of phase spectra of FBGs was derived from the general arctan function for both weak and strong FBGs. Then spectral features of FBG based Fabry-Perot cavities (FBG-FP) were investigated by introducing a new conception of the equivalent cavity length similar to general F-P cavities. Finally, an experimental scheme to measure and analyze spectra of FBG-FP cavities was proposed and conducted, which was proven to be capable of measuring spectral curves with a high accuracy.