For example, typical operating voltage of a standard 150mW red laser diode is 2. The electrical characteristics of the laser diode result in a voltage across the diode and that voltage is dependent on wavelength, optical power, and the type of laser diode. Environmental temperature as well as the temperature rise that results from the electrical power dissipation in the laser. The optical power value, Po, is the most basic characteristic of a laser diode. From the diagram it. A laser diode (LD, also injection laser diode or ILD or semiconductor laser or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction.