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Stimulated emission was a theoretical discovery by Albert Einstein within the framework of the old quantum theory, wherein the emission is described in terms of photons that are the quanta of the EM field. [5] [6] Stimulated emission can also occur in classical models, without reference to photons or quantum-mechanics.
Stimulated emission depletion (STED) microscopy is one of the techniques that make up super-resolution microscopy. It creates super-resolution images by the selective deactivation of fluorophores , minimizing the area of illumination at the focal point, and thus enhancing the achievable resolution for a given system. [ 1 ]
Stimulated emission (also known as induced emission) is the process by which an electron is induced to jump from a higher energy level to a lower one by the presence of electromagnetic radiation at (or near) the frequency of the transition. From the thermodynamic viewpoint, this process must be regarded as negative absorption.
The first device using amplification by stimulated emission operated at microwave frequencies, and was called a maser, for "microwave amplification by stimulated emission of radiation". [11] When similar optical devices were developed they were first called optical masers , until "microwave" was replaced by "light" in the acronym, to become laser .
Namely, a concerted emission of phonons can lead to coherent sound and an example of concerted phonon emission is the emission coming from quantum wells. This stands in similar paths with the laser where a coherent light can build up by the concerted stimulated emission of light from a lot of atoms. A SASER device transforms the electric ...
The term is an acronym for microwave amplification by stimulated emission of radiation. Nikolay Basov , Alexander Prokhorov and Joseph Weber introduced the concept of the maser in 1952, and Charles H. Townes , James P. Gordon , and Herbert J. Zeiger built the first maser at Columbia University in 1953.
The rate at which stimulated emission occurs is proportional to the number of atoms N 2 in the excited state, and the radiation density of the light. The base probability of a photon causing stimulated emission in a single excited atom was shown by Albert Einstein to be exactly equal to the probability of a photon being absorbed by an atom in ...
Stimulated emissions between upper and lower groups, essential for gain, require the upper levels to be more populated than the corresponding lower ones. This situation is called population-inversion. It is more readily achieved if unstimulated transition rates between the two groups are slow, i.e. the upper levels are metastable. Population ...