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
Sound amplification by stimulated emission of radiation Therefore, amplification and cooling occur around a tunable line center, in contrast with some cavity optomechanical phenomena. The creation of these finely spaced levels does not require increasing the optical microcavity dimensions. Hence, these finely spaced levels do not affect the optomechanical interaction strength in a significant degree. The approach uses intermodal coupling, induced by radiation pressure and can also provide a spectrally selective mean to detect phonons. Moreover, some evidences of intermodal cooling are observed in this kind of experiments and thus, there is an interest in optomechanical cooling. Overall, an extension to multilevel systems using multiple coupled resonators