Optical decay
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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 pnonon. Optical decay is dominant mechanism of quenching of excitation of active optical media. In solid-state lasers the optical decay limits the storage of energy in active medium.
Also, the term optical decay is used tof the effect of quick reduction of liminosity of astrophysical objects [1]
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[edit] 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 retails the evolution of islated quantum-mechanical systems which show the optical decay.
[edit] Shape of specral line at the optical decay of an idealized atom
The "isolated" quantum system (atom, ion, molecue or even a quantum dot) may have metastable states, weakly coupled to the outher world. (Some couliknd should be taken into account; overwice, tehre is no optical decay.) In the idealized case, the evolution of the system is disturbed obly by the interaciton with the continuum of the modes of the electromagnetic field. Then, the wpectral width of the emitted fohtons is determined by the relaxation rate. For the narrow spectral lines, the decay is almost exponential; then, the profile of the spectral line is determinet by the Fourier-transform of the exponential decay of the quantum amplitude of probability that the system is still excited; this profile is Lorentian. [2] [3]
[edit] Deformed vacuum
The decay rate can be affected by the distortion of uniform density of states of photons, due, for example, an external cavity [4] or a nanofiber located in vicinity of the atom [5].
[edit] References
- ^ http://edoc.mpg.de/199219 DOI:10.1051/0004-6361.20034409
- ^ V.Weisscopf, E.Wigner. Berechnung der naturlichen Lichtteorie, Ztschr. Phys. 63, 54-73 (1930)
- ^ Elementary Decay Process. http://en.wikisource.org/wiki/Elementary_Decay_Process_%28Kouznetsov%29#Schroedinger_equation_and_single-photon_states
- ^ 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
- ^ L.P.Nayak; P.N.Melentiev, M.Morinaga*, F.L.Klein, V.I.Balykin, K.Hakuta. (2007). "Optical nanofiber as an efficient tool for manipulating and probing atomic fluorescence". Optics Express 15: 5431–5438. doi:.
