Principles of Laser Operation

Abstract

The term laser, an acronym for light amplification by the stimulated emission of radiation, first appeared in 1960 and is generally held to have been coined by Gordon Gould, one of the early pioneers of laser development. Since the device was based on the same principles as the maser, a microwave source which had been developed in the 1950’s, the term ‘optical maser’ was also in usage for a time, but was rapidly replaced by the simpler term. In order to appreciate the concepts of laser action, we need to develop an understanding of the important term ‘stimulated emission’. First, however, it will be helpful to recap on the basic quantum mechanical principles associated with the absorption and emission of light. Although these principles apply equally to individual ions, atoms or molecules, it will save unnecessary repetition in the following discussion if we simply refer to molecules.

And the atoms that compose this radiance do not travel as isolated individuals but linked and massed together

‘De Rerum Naturae’, Lucretius