Longitudinal Mode Competition and Asymmetric Gain Saturation in Semiconductor Injection Lasers. I. Experiment

Abstract

Longitudinal mode competition in transverse-mode-controlled laser diodes has been experimentally investigated. A careful examination of the output power change associated with both random mode switching and hysteretic mode jumping has revealed a peculiar feature of mode competition in laser diodes; in most devices, the output power is decreased as the lasing mode jumps from a shorter to a longer wavelength mode, which it is increased at mode jumping toward shorter wavelengths. The peculiar feature has been interpreted in terms of an asymmetry in gain saturation, which was experimentally observed. A terminal voltage change associated with mode jumping has also been measured. In some devices, a small shift of the beam profile was observed at mode jumping.