imported>Loooke: /* Shape of specral line at the optical decay of an idealized atom */ specral → spectral

2021-12-02T06:52:35Z

Shape of specral line at the optical decay of an idealized atom: specral → spectral

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'''Optical decay''' is process of relaxation of excitation of an excited quantum system, usually due to the [[spontaneous emission]] of a [[photon]] or a [[phonon]].
Optical decay is dominant mechanism of quenching of excitation of active optical media. In [[solid-state laser]]s the optical decay limits the storage of energy
in active medium.

Also, the term '''optical decay''' is used to the effect of quick reduction of luminosity of astrophysical objects
<ref name="a">
http://edoc.mpg.de/199219 {{doi|10.1051/0004-6361.20034409}}
</ref>

==Phenomenology of optical decay==
In the first approximation, the optical decay can be treated as just [[spontaneous emission]], and its rate is determined with the [[Einstein Coefficients]].
For the most of laser systems, the effects of [[decoherence]] determine the spectral width of the emitted photons, and there is no reason to
consider in detail the evolution of isolated quantum-mechanical systems which show the optical decay.

==Shape of spectral line at the optical decay of an idealized atom==
The "isolated" quantum system (atom, ion, molecule or even a quantum dot) may have metastable states, weakly coupled to the outer world.
(Some couliknd should be taken into account; otherwise, there is no optical decay.) In the idealized case, the evolution of the system is disturbed only by the interaction
with the continuum of the modes of the electromagnetic field. Then, the spectral width of the emitted photons is determined by the relaxation rate.
For the narrow spectral lines, the decay is almost exponential; then, the profile of the spectral line is determined by the [[Fourier transform]] of the [[exponential decay]]
of the quantum amplitude of probability that the system is still excited; this profile is Lorentian.
<ref name="W">
V.Weisscopf, E.Wigner. Berechnung der naturlichen Lichtteorie, Ztschr. Phys. 63, 54-73 (1930)
</ref>
<ref name="D">
Elementary Decay Process.
http://en.wikisource.org/wiki/Elementary_Decay_Process_%28Kouznetsov%29#Schroedinger_equation_and_single-photon_states
</ref>

==Deformed vacuum==
The decay rate can be affected by the distortion of uniform density of states of photons, due, for example, an external cavity
<ref name="roh">
H. Rohde, J. Eschner, F. Schmidt-Kaler, R. Blatt
Optical decay from a Fabry-Perot cavity faster than the decay time.
[[JOSA B]],

http://josab.osa.org/abstract.cfm?id=69013
</ref>
or a nanofiber located in vicinity of the atom
<ref name="nayak07">{{cite journal
| url=http://www.opticsinfobase.org/abstract.cfm?URI=oe-15-9-5431
| vauthors = Nayak KP, Melentiev PN, Morinaga M, Kien FL, Balykin VI, Hakuta K
| title=Optical nanofiber as an efficient tool for manipulating and probing atomic fluorescence
| journal=[[Optics Express]]
| volume=15
| pages=5431–5438
| year=2007
| doi=10.1364/OE.15.005431
| issue=9
|bibcode = 2007OExpr..15.5431N
| pmid=19532797| doi-access=free
}}</ref> or by simply placing the system near a dielectric or metallic boundary.

==References==
<references/>

[[Category:Laser science]]

Optical decay - Revision history

imported>Loooke: /* Shape of specral line at the optical decay of an idealized atom */ specral → spectral