Two-wave mixing in chiral dye-doped nematic liquid crystals.

Two-wave mixing in nematic liquid crystals doped with dyes and chiral agents is studied. The photo-induced spatial modulation of the chiral structure, together with the diffusion anisotropy of the mixture, determine a relatively fast response time, a spatial resolution of 1 μm, and a maximum gain for circularly polarized interacting beams. The gain is insensitive to changes in linear polarization, while it varies with the grating period and with the pump-to-signal intensity ratio.