Develops, manufactures, and provides fiber-coupled diode lasers, solid-state lasers, high-power fiber patch cable and fiber-optic combiner. The products are applied in research, industry, medical and defense. Also, please take a look at the list of 47 laser diode manufacturers and their company rankings. What Is a Laser Diode? What Is a Laser Diode? A laser diode is a device. A Laser Diode is a type of semiconductor device that produces coherent light through the process of stimulated emission. Semiconductor diodes are electronic devices that conduct electricity primarily. According to Expert Market Research, the top laser diode companies are Coherent, Inc., IPG Photonics Corporation, OSRAM, TRUMPF, and Jenoptik AG, among others.