Diode, a device that allows current in only one direction. The diode is made up of a semiconductor material. When supply is given, the diode allows current in only one direction. This is called Forward bias. In Reverse bias, the current will not flow. Similarly, a Laser diode is a kind of optical diode. This converts an electrical signal into light. A laser diode is made up of PN Junction layer. The PN junction acts as a laser medium. The laser diode is made up of Gallium Arsenide. Selenium, Aluminium, and Silicon are used as a doping agent.
This is quite similar to LED. The laser diode emits coherent light with high intensity.