High brightness, high power, semiconductor lasers have many potential applications such as: free space communications,
printing, material processing, pumping etc . Such applications require lasers, which are characterized by reliability
and long lifetime.
Catastrophic optical mirror damage (COMD) process is one of the major mechanisms, which drastically limits laser
lifetime and emitted optical power . Mirror degradation and eventually destruction of lasers is caused by facet heating
due to nonradiative surface recombination of carriers. Facet heating reduces the band gap energy, consequently
increasing the absorption coefficient at the facet. The absorbed light and photo-induced electron-hole pair are increased
by the increase in the absorption coefficient. Both effects lead to further nonradiative recombination of carriers which
induces heating and so on, up to degradation of mirror or even destruction of laser. We see that this effect is very
undesirable and knowledge of the temperature dissipation on the surface is very important for improving
semiconductor lasers design. In this work we present the analysis of temperature distribution at the front facet of the
broad area GaAsP/AlGaAs lasers by means of micro-Thermoreflectance (μTR) Spectroscopy.
Several methods proved to be useful in determining the temperature of the laser surface. These are micro-probe band-to-band
photoluminescence, thermoreflectance spectroscopy and Raman spectroscopy [2, 3, 4, 5]. We have used μTR
because it is contactless, non-destructive technique which enables us to obtain temperature distribution in real time.