Sound amplification by stimulated emission of radiation a regime in which the phonon plays the role of Stokes wave. Stokes wave refers to a non-linear and periodic surface wave on an inviscid fluid (ideal fluid assumed to have no viscosity) layer of constant mean depth. For this reason it should be also possible to controllably switch between phonon and phonon laser regimes. Compound optical microcavity systems provide beneficial spectral controls. These controls impact both phonon laser action and cooling and define some finely spaced optical levels whose transition energies are proportional to phonon energies. These level spacings are continuously tunable by a significant adjustment of optical coupling.
Stimulated emission Stimulated emission Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron (or other excited molecular state), causing it to drop to a lower energy level. The liberated energy transfers to the electromagnetic field, creating a new photon with a phase, frequency, polarization, and direction of travel that are all identical to the photons of the incident wave. This is in contrast to spontaneous emission, which occurs at random intervals without regard to the ambient electromagnetic field. The process is identical in form to atomic absorption in which the