Lasing in active, sub-mean-free path-sized systems with dense, random, weak scatterers

Prasad, Raghavendra B and Ramachandran, Hema and Sood, Ajay Kumar and Subramanian, CK and Kumar, Narendra (1997) Lasing in active, sub-mean-free path-sized systems with dense, random, weak scatterers. In: Applied Optics Appl Optic, 36 (30). pp. 7718-7724.

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Abstract

We report enhanced emission and gain narrowing in Rhodamine 590 perchlorate dye in an aqueous suspension of polystyrene microspheres. A systematic experimental study of the threshold condition for and the gain narrowing of the stimulated emission over a wide range of dye concentrations and scatterer number densities showed several interesting features, even though the transport mean free path far exceeded the system size. The conventional diffusive-reactive approximation to radiative transfer in an inhomogeneously illuminated random amplifying medium, which is valid for a transport mean-free path much smaller than the system size, is clearly inapplicable here. We propose a new probabilistic approach for the present case of dense, random, weak scatterers involving the otherwise rare and ignorable sub-mean-free-path scatterings, now made effective by the high gain in the medium, which is consistent: with experimentally observed features. (C) 1997 Optical Society of America.

Item Type:	Journal Article
Publication:	Applied Optics Appl Optic
Publisher:	Optical Society of America
Additional Information:	Copyright of this article belongs to Optical Society of America.
Keywords:	Random-amplifying medium;lasing;sub-mean-free path.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	18 Oct 2011 04:35
Last Modified:	18 Oct 2011 04:35
URI:	http://eprints.iisc.ac.in/id/eprint/38284

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