Novel interleaved sampled grating mirrors for widely tunable DBR lasers

Novel sampled grating mirrors with interleaved gratings (ISGs) are proposed for the realisation of widely tunable DBR lasers based on the Vernier principle. The ISG design parameters used to control the spacing of the peaks and the shape of the maximum reflectivity envelope are presented in a design example of a widely tunable DBR laser. The simulated performances of ISG-DBR are compared with those of a sampled grating-DBR laser with the same length and the same maximum reflectivity for each mirror. The advantages gained from interleaving are discussed, paying particular attention to the static characteristics in the tuning range. It is shown that ISGs limit the threshold current variations in the coarse tuning operation mode because of the flatter envelope of the reflectivity maxima and can be useful to reduce the output power variations in the continuous tuning operation mode