“Laser diodes can create lasting conditions when pumped with electrical current at the diode junctions.”
What “lasting conditions” are you referring to? What is “pumped” electrical current?
Here is an example of operational details explained at the technical level I am expecting from engineering students:
Laser diodes have an intrinsic (un-doped silicon or germanium) layer sandwiched in between the P and N doped regions. The boundaries between the intrinsic region and the P and N regions are reflective like a mirror.
When the electrons and holes recombine in the intrinsic region during forward current through the diode, the energy lost by that recombination is emitted in the form of a photon. These photons collide with other incoming electrons, which produces even more photons. Each emitted photon bounces back and forth between the two reflective boundaries, which concentrates and guides them until they emerge as coherent light. A lens further focuses the beam.
