Laser science the laser and maser in 1917, via a paper in which he re-derived Max Planck’s law of radiation using a formalism based on probability coefficients (Einstein coefficients) for the absorption, spontaneous emission, and stimulated emission of electromagnetic radiation. The existence of stimulated emission was confirmed in 1928 by Rudolf W. Ladenburg. In 1939, Valentin A. Fabrikant made the earliest laser proposal. He specified the conditions required for light amplification using stimulated emission. In 1947, Willis E. Lamb and R. C. Retherford found apparent stimulated emission in hydrogen spectra and effected the first demonstration of stimulated emission; in 1950, Alfred Kastler
Sound amplification by stimulated emission of radiation of the resonator. The radiation then, propagates along an axis parallel to the plane defined by the two resonator walls. The static electric field acting on the liquid with gas bubbles results in the deformation of dielectrics and therefore leads to a change in the volumes of the particles. We note that, the electromagnetic waves in the medium propagate with a velocity much greater than the velocity of sound in the same medium. This results to the assumption that the effective pump wave acting on the bubbles does not depend on the spatial coordinates. The pressure of a wave pump