Round-trip loss: Difference between revisions
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In [[laser physics]], the '''round-trip loss''', or '''background loss''' <math>~\beta~</math> determines, what part of the energy of the [[laser field]] | In [[laser physics]], the '''round-trip loss''', or '''background loss''' <math>~\beta~</math> determines, what part of the energy of the [[laser field]] | ||
becomes unusable at each round-trip; it can be absorbed or scattered. | becomes unusable at each round-trip; it can be absorbed or scattered. | ||
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<math>~g=\beta+\theta~</math> | <math>~g=\beta+\theta~</math> | ||
Such as relation is used in analytic estimates of the performance of lasers | Such as relation is used in analytic estimates of the performance of [[laser|lasers]] | ||
<ref name="uns">{{cite journal | <ref name="uns">{{cite journal | ||
| author=D.Kouznetsov | | author=D.Kouznetsov | ||
Revision as of 15:36, 10 January 2009
In laser physics, the round-trip loss, or background loss determines, what part of the energy of the laser field becomes unusable at each round-trip; it can be absorbed or scattered.
At the self-pulsation, the gain lates to respond the variation of number of photons in the cavity. Within the simple model, the round-trip loss and the output coupling determine the damping parameters of the equivalent oscillator Toda [1] [2].
At the steady-state operation, the round-trip gain exactly compensate both, the output coupling and losses: . Assuming, that the gain is small (), this relation can be written as follows:
Such as relation is used in analytic estimates of the performance of lasers [3]. In particular, the round-trip loss may be one of important parameters which limit the output power of a disk laser; at the power scaling, the gain should be decreased (in order to avoid the exponential growth of the amplified spontaneous emission), and the round-trip gain should remain larger than the background loss ; this requires to increase of the thickness of the slab of the gain medium; at certain thickness, the overheating prevents the efficient operation [4][5].
For the analysis of processes in active medium, the sum can be also called "loss" [6]. This notation leads to confusions as soon as one is interested, which part of the energy is absorbed and scattered, and which part of such a "loss" is actually wanted and useful output of the laser.
References
- ↑ G.L.Oppo; A.Politi (1985). "Toda potential in laser equations". Zeitschrift fur Physik B 59: 111–115. DOI:10.1007/BF01325388. Research Blogging.
- ↑ D.Kouznetsov; J.-F.Bisson, J.Li, K.Ueda (2007). "Self-pulsing laser as oscillator Toda: Approximation through elementary functions". Journal of Physics A 40: 1–18. DOI:10.1088/1751-8113/40/9/016. Research Blogging.
- ↑ D.Kouznetsov; J.-F.Bisson, K.Takaichi, K.Ueda (2005). "Single-mode solid-state laser with short wide unstable cavity". JOSAB 22 (8): 1605–1619. DOI:10.1364/JOSAB.22.001605. Research Blogging.
- ↑ D. Kouznetsov; J.-F. Bisson, J. Dong, and K. Ueda (2006). "Surface loss limit of the power scaling of a thin-disk laser". JOSAB 23 (6): 1074–1082. DOI:10.1364/JOSAB.23.001074. Retrieved on 2007-01-26. Research Blogging.
- ↑ D.Kouznetsov; J.-F.Bisson (2008). "Role of the undoped cap in the scaling of a thin disk laser". JOSA B 25 (3): 338-345. DOI:10.1364/JOSAB.25.000338. Research Blogging.
- ↑ A.E.Siegman (1986). Lasers. University Science Books. ISBN 0-935702-11-3.