OPTICAL-PHASE CONJUGATION IN DYE-DOPED NEMATIC LIQUID-CRYSTAL

Optical phase conjugation in dye-doped nematic liquid crystals has bee n obtained with 532 nm radiation from a cw doubled YAG laser of total power of 50 mW, A 40 degrees twisted nematic cell configuration has be en used, The degenerate four-wave mixing (DFWM) experiment allowed for measurements of build-up time of phase conjugate signal and phase con jugate reflectivity as a function of input beam intensities and gratin g spacing. The PC reflectivities reached 2.6% and build-up times were of the order of 200 ms. The origin of the phase conjugate signal is li nked with photoconductivity enhanced dynamic holographic refractive in dex grating formation observed in this and other similar systems. (C) 1998 Elsevier Science B.V.