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

Journal Article · Wed Oct 01 04:00:00 EDT 1997 · Applied Optics

DOI:https://doi.org/10.1364/AO.36.007718· OSTI ID:678695

Raghavendra Prasad, B; Sood, Ajay Kumar; Subramanian, C K ^[1]; Kumar, Narendra ^[2]

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1. Department of Physics, Indian Institute of Science, Bangalore 560012 (India)
2. Raman Research Institute, Bangalore 560080 (India)

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. {copyright} 1997 Optical Society of America

• OSTI ID: 678695
• Journal Information: Applied Optics, Journal Name: Applied Optics Journal Issue: 30 Vol. 36; ISSN APOPAI; ISSN 0003-6935
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
DESIGN
DYE LASERS
DYES
GAIN
OPTICAL PUMPING
RHODAMINES
STIMULATED EMISSION
VISIBLE SPECTRA