n this work we investigate the catastrophic optical damage (COD) of GaAS based quantum well (QW) laser diodes under the optics of the role played by the physical properties of the materials forming the active parts of the lasers in the degradation process, taking account of their nanoscale dimensionality. High power laser diodes under operation can experience local heating phenomena that lead to device failure. A thermo-mechanical model has been set up to study the mechanism of degradation. The incidence of the local heating in the degradation is tightly related to the physical properties of the active region of the laser. In particular, the thermal conductivity, the optical absorption, the thermal expansion coefficients, and the mechanical strength, play a crucial role in the degradation process. Furthermore, the low dimensionality of the layers has a strong influence on those properties.
