A semiconductor laser, also known as a laser diode, is a type of laser that uses a semiconductor as its gain medium. It operates by injecting electrical current into the semiconductor material, which causes electrons to recombine with holes, releasing energy in the form of light. This light is then amplified and emitted as a coherent beam. These lasers are widely used in various applications, including optical communication, barcode scanners, and laser printers. Their compact size, efficiency, and ability to produce specific wavelengths make them essential in modern technology, contributing to advancements in electronics and telecommunications.