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. The 1 is LD anode +, the 3 is LD cathode –, the 2 is to connect the laser diode case. Operational Mechanism: Laser diodes create light through stimulated emission within an optical cavity, with the light's properties influenced by the semiconductor. A laser diode type of diode that creates a very strong and focused beam of light.