Diode Laser Principle Eventually

Some of the photons drifting randomly in the depletion region are reflected vertically back along their original path. The reflected photons are reflected back again from the other end of the knot. The movement of the photon from one end to the other is repeated. As photons move, more atoms release more photons due to an avalanche effect. This reflection and the process of producing more and more photons produces very strong laser beams. Each photon produced during the emission process explained above is the same as other photons at the energy level, phase relationship, and frequency. Therefore, the emission process gives a single wavelength laser beam. In order to produce a laser, the current of the laser diode must exceed a certain threshold level. The current below the threshold level forces the diode to behave as an LED, emitting incoherent light.