Spectral characteristics for a fiber grating external cavity laser

A numerical investigation has been carried out on the influence of the antireflection (AR) coating of laser, the coupling efficiency of laser and fiber (eta), and the reflectivity of fiber grating (R-g) on the side-mode suppression ratio (SMSR) of the fiber grating external cavity laser (FGECL). The FGECL was fabricated by the assembly of the multimode Fabry-Perot (FP) laser chip and fiber grating. The results showed that the FGECL with a lower AR coating, higher eta and R-g exhibited a better SMSR. A comparison of the SMSR dependence on the eta and R-g showed that SMSR increased more rapidly with increasing eta than SMSR for R-g. These spectral characteristic studies of the SMSR dependence on the device parameters of the AR coating, eta, and R-g may provide useful device designs for the practical fabrication of a FGECL for use in dense wavelength division multiplexing (DWDM) applications.