Quantitative thermal imaging of GaInAsSb/AlGaAsSb laser diodes by thermoreflectance

Abstract
The performances of laser diodes operating in continuous wave regime, in terms of lifetime, output power and emission wavelength, are strongly limited by internal Joule heating. Using a CCD-based thermoreflectance system, we have obtained thermal images of laser diodes operating at various biases. Separate calibration procedures have been implemented to obtain quantitative temperatures on the gold-covered ridge waveguides and on the emission facets, thus providing a complete picture of the surface temperature of the device. The continuity of the obtained temperatures is a strong indication of the consistency of the measurements. Even in quasi-static regime, temperature inhomogeneities have been detected, which might lower the permanent damage threshold of the devices.