Selection of the fiber grating length in a fiber grating external cavity semiconductor laser

After taking into account the fact that the peak reflectivity of the fiber grating in a fiber grating external cavity semiconductor laser (FGECSL) is required to be lower than unity, the influence of the fiber grating length on the peak reflectivity has been focused on in this paper. Adopting the coupled mode theory, the dependence of the peak reflectivity on the fiber grating length has been studied numerically for various types of fiber gratings. The obtained results have important values on how to select the fiber grating length in a FGECSL.