The rate equation theory researches the basic relation of the atomic spontaneous emission, stimulated emission and stimulated absorption, and it is the fundamental theoretical calculations.

But now, the Spaser, which is an acronym for "surface plasmon amplification by stimulated emission of radiation, " has the ability to be as small as needed and can be used in future technologies.

There is a promising application in the study of stimulated emission of organic semiconductor materials such as conjugated polymer.