Lasers generate phase-coherent electromagnetic radiation at optical and infrared frequencies from external energy sources by preferentially pumping excited states of a “laser” to create an inversion in the normal distribution of energy states. Photons of a specific frequency emitted by stimulated emission enter and are amplified as standing waves in a resonant optical cavity.
The most efficient DC-to-laser converters are solid-state laser diodes commercially employed in fiber optic and free-space laser communication. Although for using a laser in space we generally need “solar pumped lasers” since the conventional gas or solid-state fuel-based lasers rely directly on electrical energy to generate laser oscillations which reduces the efficiency of laser generation in space considerably.
For larger-scale space applications for wireless power transmission, a large area emitting system with thousands of individual diodes could be it. In this case, the main limitation is the thermal control of such diode panels to maintain optical coherence(associated with interference effects of light).
