A Numerical Analysis for Optimizing the Gratings Length and Coupling Coefficient for High Reflectivity and Low Cavity Loss in Fiber Grating Fabry-Perot Laser Model

The effects of gratings length (kLFG) and amplitude coupling (Co) coefficients on the effective reflectivity (Reff) and the total cavity loss (αtot) of an external cavity laser source (ECLS) based fiber Bragg gratings (FBGs) are numerically analyzed for designing a laser source operating in strong feedback regime (Regime V). In this study, FBG is used as a wavelength selective element to control the properties of the laser output by controlling the fiber gratings reflectivity level. The study is performed by modifying full analytical expressions for the Reff and the αtot based on laser coupled-wave equations. Results show that Reff is strongly dependent on kLg and Co. Also, it is found that αtot has been reduced significantly with increasing Co, especially at high value for kLG (kLFG> 1.5).