The role of stimulated emission in luminescence decay

Alexandra Rapaport

S. Chopra, Himadri Bihari Bohidar, V. Harwalkar

Olimkhon K. Alimov, Tasoltan T. Basiev, Yu.V. Orlovskii +2 more

The luminescence and laser characteristics of a synthetic opal matrix filled with organic dyes are studied upon excitation by nanosecond laser pulses. The appearance of stimulated emission in a partially ordered scattering medium is investigated. It is shown that if the luminescence spectrum of a dye (oxazine-17) is located far outside the photonic bandgap of the opal matrix, stimulated emission along a preferential direction in the (111) plane is observed when pumping exceeds a threshold even without an external optical cavity. The stimulated emission spectrum is considerably narrower than the luminescence spectrum and consists of several narrow lines located within the dye luminescence band. If the luminescence spectrum of a dye (rhodamine 6G) overlaps with the photonic bandgap of the opal matrix, a different picture is observed. The loss of radiation in the matrix leads to the red shift of the luminescence spectrum, while the stimulated emission as in the case of oxazine-17 lies is observed within the luminescence band.

Masahiro Ojima, Takashi Kushida, Shigeo Shionoya +2 more

Various optical spectra such as time-resolved luminescence spectra are studied for excitonic molecules in CuCl under two-photon resonance excitation by using picosecond and nanosecond frequency-tunable laser pulses. Two sharp emission lines observed under resonance excitation are ascribed to the radiative decay of “cold” excitonic molecules created directly at k ∼2 k 0 , while the broad emission band on the low energy side of the sharp line to the luminescence of “hot” molecules created through single excitons. The stimulated emission process gives a considerable influence on both the sharp luminescence lines and the hot molecule band, and further on two-photon resonant excitonic Raman lines as well. Discussions are made on the Bose condensation of the excitonic molecules and also on whether the emission under just-resonance excitation is due to Raman scattering or luminescence.

Joseph R. Lakowicz, Ignacy Gryczyński

А. А. Каминский, Vladimir M. Garmash, G. A. Ermakov +3 more

The authors study the excitation of stimulated emission of Ho/sup 3 +/ ions in a single crystal of YAlO/sub 3/ by waves of inter-Stark transitions of three generation channels /sup 5/S/sub 2/ to /sup 5/I/sub 5-7/ at 300 K with optical pumping. They also measure the main luminescence characteristics.