Semiconductor lasers, also known as laser diodes, are lasers that use semiconductor materials as working materials. Due to differences in material structure, the specific process of producing lasers varies among different types. Common working materials include gallium arsenide (GaAs), Cadmium sulfide (CdS), Indium phosphide (InP), Zinc sulfide (ZnS), etc. There are three types of excitation methods: electric injection, electron beam excitation, and optical pumping. Semiconductor laser devices can be divided into several types, including homojunctions, single heterojunctions, and double heterojunctions. Homojunction lasers and single heterojunction lasers are mostly pulse devices at room temperature, while double heterojunction lasers can achieve continuous operation at room temperature.
Semiconductor diode lasers are the most practical and important type of laser. It has a small size, long lifespan, and can be pumped using a simple injection current method. Its working voltage and current are compatible with integrated circuits, so it can be integrated on a single chip. And current modulation can also be directly performed at frequencies up to GHz to obtain high-speed modulated laser output. Due to these advantages, semiconductor diode lasers have been widely used in laser communication, optical storage, optical gyroscopes, laser printing, ranging, and radar.