Mirror degradation in AlGaAs double-heterostructure lasers

Abstract

Degradation mechanism and the related change in lasing characteristics for a mirror degradation were investigated in AlGaAs double-heterostructure lasers with uncoated mirror surfaces. In constant optical-power operation, mirror degradation was classified into three phases. The lasing-characteristics degradation in the initial stage of phase I was well explained in the excitation-enhanced oxidation model. Dark-line defects, originating from mirror surfaces, were found in the final stage of phase III, following phase II with a low degradation rate. The mechanism of the optical-power dependence was also investigated. Marked improvement in operating life was confirmed by the dielectric film coating and in a new-structure laser with little excitation in the vicinity of mirror surfaces.