A laser diode is electrically a PIN diode. The active region of the laser diode is in the intrinsic (I) region, and the carriers (electrons and holes) are pumped into that region from the N and P regions respectively. While initial diode laser research was conducted on simple P–N diodes, all modern lasers use the double-hetero-structure implementation, where the carriers and the photons are confined in or. OverviewA laser diode (LD, also injection laser diode or ILD or semiconductor laser or diode laser) is a device similar to a in which a diode pumped directly with electrical current can create. Following theoretical treatments of M.G. Bernard, G. Duraffourg, and William P. Dumke in the early 1960s, light emission from a (GaAs) semiconductor diode (a laser diode) was demonstrat.