Optical absorption rate determination, on the front facet of high-power GaAs laser diodes, by means of thermoreflectance technique

Very-high-resolution thermoreflectance measurements have been used to study the light absorption occurring on the front Facet of GaAs laser diodes, wh ich is responsible for their damage. We determined the activation of the in duced surface heat source for an injected current higher than the laser emi ssion threshold current. This varying thermal behavior of the laser diode a ccording to the value of the injected current has been used to determine th e contribution to heat dissipation due to the surface source only. By ident ification using a thermal model we could evaluate for the First time the su rface absorption rate both on coated and noncoated laser diodes. We propose it as a new reliability criterion, which enables discrimination of laser d iodes both according to their coating and to their aging.