Random Laser Emission at Dual Wavelengths in a Donor-Acceptor Dye   Mixture Solution
  The work was aimed to generate random laser emissions simultaneously at two wavelengths in a weakly scattering system containing mixture of binary dyes, rhodamine-B (Rh-B) and oxazine-170 (O-170) dispersed with ZnO nano-particles served as scattering centres. Random lasing performances for individual Rh-B dye were extensively studied for varying small signal gain/scatterer density and found lasing threshold significantly depend upon number density of dispersed nano-particles. In spite of inefficient pumping, we demonstrated possibility of random lasing in O-170 dye solution on account of resonance energy transfer from Rh-B dye served as donor. At optimum concentrations of fluorophores and scatterer in dye mixture solution, incoherent random lasing was effectively attained simultaneously at two wavelengths centered 90 nm apart. Dual-emission intensities, lasing thresholds and rate of amplifications were found to be equivalent for both donor and acceptor in dye mixture solution. 
Sunita Kedia and Sucharita Sinha
physics.optics