Optimisation of a single phase-shift distributed coupling coefficient DFB laser structure near threshold regime

This paper presents a numerical procedure for the accurate optimisation of a single phase-shift (1PS) distributed coupling coefficient-distributed feedback (DCC-DFB) laser structure. The optimisation regards the main figures of merit concerning the laser single longitudinal mode operation: the normalized mode selectivity (S) and the flatness (F). The normalized threshold gain (alpha_th L) is also assessed. A step-by-step description of the numerical procedure based in matrix techniques, is performed. S = 1.8 and F = 0.020, with alpha_th L = 1.50 are achieved for the optimized 1PS-DCC-DFB laser structure, which represents a strong improvement face to the performances reported elsewhere for similar structures.