All-optical image processing with a supranonlinear dye-doped liquid-crystal film.

We demonstrate a dynamic all-optical image-intensity-inversion technique that uses self- and mutual-phase-modulation effects with a highly nonlinear nematic liquid-crystal film placed in an intermediate focal plane. This process requires submilliwatt optical power, responds in a few milliseconds, and can be realized over a very broad spectral range.

Nonlinear liquid-crystal fiber structures for passive optical limiting of short laser pulses.

Optical limiting of nanosecond and picosecond laser pulses through millimeter-length isotropic liquid-crystalcored fiber structures is reported. Low limiting threshold and clamped transmitted outputs are observed. The underlying nonlinear mechanisms are nonlinear photoabsorptions and scattering and lossy waveguiding caused by laser-induced thermal-density index fluctuations.

Coherent beam amplification with a photorefractive liquid crystal.

Coherent amplification of a signal beam by a strong pump beam is observed in thin films of fullerene-doped nematic liquid crystal. Exponential gain constants as high as 2890 cm(-1) with no phase cross talk are achieved at low applied dc bias voltage and pump beam intensity. The underlying mechanism is the electro-optically induced spatially reorientation of the liquid-crystal axis and the resultant phase-shifted index grating required for two-beam coupling.

Deformed-helix ferroelectric liquid-crystal spatial light modulator that demonstrates high diffraction efficiency and 370-line pairs/mm resolution.

New liquid-crystal media and photoconductor materials are being utilized in spatial light modulators to increase their resolution, diffraction efficiency, speed, and sensitivity. A prototypical device developed for real-time holography applications has shown an 8% diffraction efficiency from a holographic grating with a spatial frequency of 370 line pairs/mm (lp/mm). At 18 lp/mm the device has demonstrated a 31% diffraction efficiency with a 600-micros hologram write time using 400-nJ/cm(2) write beams.