ANALYSIS OF THE STABILITY OF MULTIPLE-PHASE-SHIFT DISTRIBUTED-FEEDBACK SEMICONDUCTOR-LASERS

The effects of the longitudinal spatial hole burning on the static las ing characteristics of a specific configuration of distributed-feedbac k 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 a t low output power, is predicted for drive levels beyond a critical va lue. The lasing wavelength exhibits a sudden shift (wavelength chirpin g), along with a significant degradation of the single-mode character of the longitudinal-mode spectrum. Thus, the potentialities of this mu ltiple-phase-shift structure to provide a stable narrow-linewidth emis sion at high output power appear to be less than expected from results calculated for the near-threshold regime. Nevertheless, it is found t hat a multiple-phase-shift configuration that departs slightly from th e optimum case suffices to recover most of the promises expected from this distributed-feedback laser design.