Semiconductor Lasers

The laser diode is one of the pivotal technological inventions of humanity in the 20th century, which has a wide and profound impact on various aspects of human society. Among the different types of lasers, semiconductor lasers stand out as the most significant, owing to their compact size, prolonged operational lifespans, cost-effectiveness, straightforward current injection pumping method, and compatibility with integrated circuits. The lasers boast the capability of direct modulation at speeds of tens of gigahertz (GHz), facilitating high-speed data transmission. Consequently, they find wide applications in laser communication, laser medicine, ranging, light radar, and various other fields. This review commences with an exploration of the inception and fundamental principles of lasers, with a focus on introducing the types, principles, and unique applications of semiconductor lasers based on their structural characteristics.