Thermoreflectance measurements for optically emitting devices

This work examines the difficulties associated with using optical techniques to measure temperature when the device itself emits a significant level of light over a wide spectrum, making it a challenge to separate the useful measurement signal from the device emission. The specific situation considered here is that of using a thermoreflectance (TR) thermography approach to characterize the thermal behavior of semiconductor laser devices. A lowpass filter was placed in the optical path to minimize the primary laser irradiation on the TR imaging and then the TR response of the region of interest was determined over a wide range of visible light wavelengths to locate the maximum response. TR measurements performed at the optimal light wavelength successfully provided a submicron-resolution map of the active area of sample lasers.