Analysis of the stability of multiple-phase-shift distributed-feedback semiconductor lasers

Abstract

The effects of the longitudinal spatial hole burning on the static lasing characteristics of a specific configuration of distributed-feedback semiconductor laser with three phase-shift regions are investigated using a numerical approach. A serious degradation of the stability of the optimum design, having the flattest axial intensity distribution at low output power, is predicted for drive levels beyond a critical value. The lasing wavelength exhibits a sudden shift (wavelength chirping), along with a significant degradation of the single-mode character of the longitudinal-mode spectrum. Thus, the potentialities of this multiple-phase-shift structure to provide a stable narrow-linewidth emission at high output power appear to be less than expected from results calculated for the near-threshold regime. Nevertheless, it is found that a multiple-phase-shift configuration that departs slightly from the optimum case suffices to recover most of the promises expected from this distributed-feedback laser design.