Continuous-wave amplification and light storage in optically and electrically pumped random laser media
Bin Li, Stephen Colby Rand
Gain competition is analyzed theoretically on coupled stimulated emission transitions in Λ-type configurations of excited atoms and compared with experimental observations in electrically and optically pumped random media. Under steady-state conditions, we predict and observe dramatic spectral quenching among 2F5/2 transitions in electron-beam-irradiated Nd3+:δ-Al2O3 nanopowders, identifying a simple mechanism that promotes laser action at the longest wavelength (405 nm). In optically pumped Nd3+:Y2O3 nanopowder, simultaneous laser action is observed at two previously unreported wavelengths of Nd3+ (763 and 821 nm), but spectral quenching is not observed, owing to the absence of Λ coupling among the inverted transitions. Quantitative analysis of quenching and threshold behavior in the case of Nd3+:δ-Al2O3 indicates that in wavelength-sized volumes of these light-confining media the average storage time of light may be as long as 30 ps.
Journal of the Optical Society of America B•Mar 15, 2007•2 citations