Forward electrical bias across the laser diode causes the two species of charge carrier – holes and electrons – to be injected from opposite sides of the PIN junction into the depletion region. Holes are injected from the p -doped into the undoped (i) semiconductor, and electrons vice versa.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. A laser diode is electrically a. 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 respectivel.