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 resulting from the distribution of velocities in a gas at a certain temperature. This has a Gaussian shape and reduces the peak strength of the line shape function. In a practical problem the full line shape function can be computed through a convolution of the individual line shape functions involved. Therefore, optical amplification will add power to an incident optical field at frequency formula_17 at a rate given by The stimulated emission cross section is where Stimulated emission can provide a physical mechanism for optical amplification. If an external source of energy stimulates more than 50% of the atoms in