Microthermographic investigations of aging processes in diode lasers

摘要

The application of multi-spectral microthermography to the monitoring of aging processes in diode lasers is reported. We have found that an intensity of the luminescence in near IR (1.5 - 2 micron range) increases with the operational time, which tentatively is correlated with increased concentration of point defects. This effect is monitored with a specially configured thermographic camera. The set-up provides spatially resolved information about the luminescence that originates from radiative recombination at defect centers as well as the pure thermal emission. In order to elucidate the role of point defects in the aging process of diode laser complementary spectroscopic measurements are performed. Photocurrent spectroscopy is used to examine the absorption properties of laser structure for fresh as well for aged devices. The results of low-current Ⅰ-Ⅴ characterization are presented. A correlation between measurement results obtained using different methods is found, discussed and interpreted in detail.