Voltage change across the self-coupled semiconductor laser

The results of experimental and theoretical analyses on the voltage changes across the GaAlAs semiconductor laser diodes caused by the onset of optical feedback are described. The dependence of voltage changes on the injection current and on the feedback ratio indicates that the origins of the voltage changes are the photoconduction effect and a reduction of the quasi-Fermi level related to the enhanced stimulated emission. The calculated voltage changes based on the theoretical analyses using the published laser parameters are in good agreement with the experimental ones. The preferable specifications for a laser diode (LD) to exhibit a larger voltage change at the onset of optical feedback are discussed.