Enhancement of dye fluorescence recovery in nematic liquid crystals using a spatial optical soliton

Up to now, spatial optical solitons have been mostly studied for their particular nature (a nonlinear mode of propagation); with a potential application in steering and routing beams. In this paper, we propose another use of spatial optical solitons: the enhancement of the fluorescence recovery. As a spatial soliton can be excited in a luminescent medium, the luminescence excited by this collimated beam will be partly trapped within the self created waveguide and then driven up to a collection fiber facing the soliton. We demonstrate the feasibility of such concept by comparing the collected fluorescence signals of a dye in a nematic liquid crystal host, excited either by a Gaussian beam or a spatial soliton, in both cases, emerging out of a source fiber and collected via another fiber. We found that, the fluorescence signal collected as the excitation source, is a soliton, is larger than the one collected as the source, is a Gaussian beam, with an enhancement factor which depends on the fibers distance. Actually, we found that, for a soliton excitation source, the signal slightly increases as the distance between the fibers varies from 0.5 to 2 Rayleigh range, contrarily to the case of a Gaussian beam excitation source for which the signal severely decreases with that distance. A simple model confirms such a behavior. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3446091]