Stimulated Definition and 61 Threads

Stimulated emission is the process by which an incoming photon of a specific frequency can interact with an excited atomic electron (or other excited molecular state), causing it to drop to a lower energy level. The liberated energy transfers to the electromagnetic field, creating a new photon with a phase, frequency, polarization, and direction of travel that are all identical to the photons of the incident wave. This is in contrast to spontaneous emission, which occurs at random intervals without regard to the ambient electromagnetic field.
The process is identical in form to atomic absorption in which the energy of an absorbed photon causes an identical but opposite atomic transition: from the lower level to a higher energy level. In normal media at thermal equilibrium, absorption exceeds stimulated emission because there are more electrons in the lower energy states than in the higher energy states. However, when a population inversion is present, the rate of stimulated emission exceeds that of absorption, and a net optical amplification can be achieved. Such a gain medium, along with an optical resonator, is at the heart of a laser or maser.
Lacking a feedback mechanism, laser amplifiers and superluminescent sources also function on the basis of stimulated emission.

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  1. A

    In stimulated emission how does the incident photon make release of

    In stimulated emission how does the incident photon make release of other photon from another atom? advanced thanks.
  2. P

    Stimulated photons direction: book suggestion.

    Hi everyone! I will very thankful to whom can suggest me some texts or webpages where I can find a demonstrated explanation of why photons emitted by stimulated atoms travels in same direction of the photons which interact with the atoms. Every author says photons are coherent, same phase...
  3. A

    Can you explain the phenomenon of stimulated emission in lasers?

    I am interested in learning the nature of the interaction between a photon and the atoms in a medium that has undergone population inversion that causes stimulated emission i.e. if an excited-state atom is perturbed by a photon (with an electric field of specific frequency), why does it emit an...
  4. A

    Fraction of stimulated photons that escape from a laser cavity

    How to calculate the fraction of stimulated photons that escape from a laser cavity with alpha=0.1 cm^-1 length of cavity=1mm refractive index of laser cavity=3.2 the photons are assumed to be escaping into air so approx refractive index is 1. Im assuming that alpha is some sort of...
  5. V

    Gas Laser: Stimulated Emission and Positive Ions

    In a gas laser, an electron in the highest energy state absorbs photon for stimulated emission to occur, but now since it has more energy than its highest state, shouldn't it escape the atom and the active medium be left only with positive ions?
  6. S

    Stimulated Emission: Why Are Photons In Phase?

    Hi. I can't see why the photon created by stimulated emission in a common laser should be in phase and with the same polarization of the original photon. Thank you.
  7. S

    Stimulated Emission: Intuitive Explanation Needed

    I am trying to find an intuitive explanation for the stimulated emission phenomenon. I know the effect: a photon with the right frequency "interacts" with an excited electron to create a copy of itself( same phase, same amplitude, same state) putting the electron to a lower energy state... But...
  8. E

    Units for Einstein coefficients in stimulated emission?

    Homework Statement Hi, I need to know the correct SI units for Einstein Coefficients (A and B) for stimulated emission (say laser). The equation I'm on about is Homework Equations \frac{A}{B} = \frac{8\pi h\nu^{3}}{c^{3}}The Attempt at a Solution after some scribbling I got to \frac{A}{B}...
  9. F

    Do spontaneous and stimulated emission obey to a Boltzmann's statistics ?

    Are spontaneous and stimulated emission selected by a Boltzmann's statistics ? Consider 2 levels(m,n) oscillators in thermal equilibrium with Einstein's coefficients Amn (spontaneous emission), Bmn (stimulated emission), Bnm (absorption) and r(f) the energy density at the frequency f (black...
  10. deccard

    Stimulated emission. Energy of the photon inducing the emission.

    In order to produce stimulated emission we need a photon which has the same energy as the difference is the lower and upper energy levels in the excited atom. But how exactly the energy of the photon does have to correspond to the energy difference between the levels. Can stimulated emission...
  11. K

    Energy level jump in stimulated emision

    when some energy is suplied to an electron in a higher energy level E2 then how come it drops down to a lower energy level E1 but as per our knowlwdge of physics...it should jump to a higher energy level E3.
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