A laser diode is a semiconductor device that emits coherent light through the process of stimulated emission. When electric current flows through the p-n junction, the gain is. Key performance characteristics are thoroughly explored, including emission bandwidth, wavelength tuning via temperature or current, voltage-current characteristics, and the very high wall-plug efficiency. Further topics include the often poor beam quality of high-power devices and the need for. A laser diode (semiconductor laser) is an electronic component that generates laser light by converting electric current into light using a semiconductor p-n junction. This junction is known as a p-n junction.