Sound amplification by stimulated emission of radiation Such values approach the electric puncture intensity of liquid dielectrics. Hence, a study proposes a SASER scheme without this limitation. The pumping is created by radial mechanical pulsations of a cylinder. This cylinder contains an active medium—a liquid dielectric with gas bubbles. The radiation emits through the faces of the cylinder. A proposal for the development of a phonon laser on resonant phonon transitions has been introduced from a group in Institute of Spectroscopy in Moscow, Russia. Two schemes for steady stimulated phonon generation were mentioned. The first scheme exploits a narrow - gap indirect semiconductor or analogous indirect gap
Stimulated emission quantum theory, wherein the emission is described in terms of photons that are the quanta of the EM field. Stimulated emission can also occur in classical models, without reference to photons or quantum-mechanics. (See also Laser#history ) Stimulated emission can be modelled mathematically by considering an atom that may be in one of two electronic energy states, a lower level state (possibly the ground state) (1) and an "excited state" (2), with energies "E" and "E" respectively. If the atom is in the excited state, it may decay into the lower state by the process of spontaneous emission, releasing the