Formation of photovoltaic bright spatial soliton in photorefractive LiNbO3 crystal by a defocused laser beam induced by a background laser beam

Abstract

We have shown, for the first time to our knowledge, both theoretically and experimentally that a bright photovoltaic (PV) spatial soliton (SS) can be formed in a photorefractive crystal with large Glass constant and negative refractive index perturbation, provided that the Glass constant of the background beam is larger than that of the self-trapped (signal) beam. The ratio of the effective Glass constants of the self-trapped beam and the background beam is the key parameter that determines whether the PV SS is bright or dark. We have demonstrated experimentally that bright SSs can be formed in LiNbO3 crystals using all four combinations of polarizations of the signal beam and the background beam.