Impact ionization coefficients for electrons and holes in InP were measured experimentally at 25-175 ·C in the 400-600 kV /cm electric field range with planar avalanche photodiodes, in which the n-InP avalanche region was separated from the light absorbing InGaAs and/or InGaAsP layers. a and P monotonically decreased with elevated temperatures; P / a slightly decreased with increasing temperature. Comparison of the experimental results with Okut

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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.