Two lasing modes are observed for Sulforhodamine 640 in highly scattering media pumped by 3-ns 532-nm laser pulses. The stimulated-emission thresholds are found to depend on both concentration of laser dye and scattering particle density. At 2.5 × 10-2 M dye solution with TiO2 scattering nanoparticles from 5 × 109 cm-3 to 1011 cm-3, the thresholds are found to decrease by more than 2 orders of magnitude. The dominating lasing modes are found to switch from 650 to 620 nm with the increase of density of scatterers.
© 1996 Optical Society of America
W. L. Sha, C.-H. Liu, Feng Liu, and R. R. Alfano, "Competition between two lasing modes of Sulforhodamine 640 in highly scattering media," Opt. Lett. 21, 1277-1279 (1996)