Continuous-wave amplification and light storage in optically and electrically pumped random laser media

摘要

Gain competition is analyzed theoretically on coupled stimulated emission transitions in A-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 F-2(5/2) transitions in electron-beam-irradiated Nd3+: delta-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 A coupling among the inverted transitions. Quantitative analysis of quenching and threshold behavior in the case of Nd3+: delta-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. (c) 2007 Optical Society of America.