Laser diodes are the most common type of lasers produced, with a wide range of uses that include fiber-optic communications, barcode readers, laser pointers, CD / DVD / Blu-ray disc reading/recording, laser printing, laser scanning, and light beam illumination. A laser diode (or diode laser) is a semiconductor device that undergoes stimulating emission to emit coherent light. It works on the same basic principle as an LED, but with an internal structure that forces photons to align in phase and direction, producing coherent laser light instead of the. This section provides an overview for laser diodes as well as their applications and principles. Here are the top-ranked laser diode companies as of May, 2026: 1.