diodlaser

A diode laser, or laser diode, is a semiconductor device that emits laser light when an electric current passes through it. The active medium is a p-n junction, engineered to provide optical gain and feedback in a resonant cavity, producing coherent light. Diode lasers include edge-emitting varieties and vertical-cavity surface-emitting lasers (VCSELs).

Construction and operation: The active region is usually a multiple quantum well stack of III-V materials such as GaAs or InP. The optical cavity is formed by cleaved facets or by distributed Bragg reflectors; VCSELs use internal mirrors. Light is emitted from the semiconductor by current injection, and temperature control stabilizes wavelength and power.

Wavelengths and performance: Diode lasers span visible to near-infrared light. Common telecom devices operate around 850, 1300 and 1550 nm. Output powers range from milliwatts for small devices to tens of watts for high-power stacks; wall-plug efficiency varies with design. Beam quality is excellent in single-mode diodes and more challenging in multimode devices.

Variants and usage: Edge-emitting diodes are compact and often used in modules with external optics; VCSELs produce circular beams and arrays suitable for 2D imaging and short-reach links. Diode lasers are widely integrated in telecommunications, data storage (CD/DVD/Blu-ray drives), printers, barcode scanners, and industrial processing.

Safety and reliability: Diode lasers require safeguards for eye and skin exposure, with regulatory standards governing classification, labeling and protective measures. Modern devices can offer tens of thousands of hours of operation, depending on current, temperature and duty cycle.