Sound amplification by stimulated emission of radiation be more conceivable by imagining it in analogy to laser theory. Theodore Maiman operated the first functioning LASER on May 16, 1960 at Hughes Research Laboratories, Malibu, California, A device that operates according to the central idea of the "sound amplification by stimulated emission of radiation" theory is the "thermoacoustic laser". This is a half-open pipe with a heat differential across a special porous material inserted in the pipe. Much like a light laser, a thermoacoustic SASER has a high-Q cavity and uses a gain medium to amplify coherent waves. For further explanation see thermoacoustic heat engine. The possibility of
Sound amplification by stimulated emission of radiation an optical cavity, but in a different active medium. An example of an active medium is the superlattice. A superlattice can consist of multiple ultra-thin lattices of two different semiconductors. These two semiconductor materials have different band gaps, and form quantum wells—which are potential wells that confine particles to move in two dimensions instead of three, forcing them to occupy a planar region. In the superlattice, a new set of selection rules is composed that affects the flow-conditions of charges through the structure. When this set-up is excited by a source, the phonons start to multiply while they reflect on