Opto-optical modulation in N-(p-methoxybenzylidene)-p-butylaniline

A method of opto-optical modulation in liquid crystals is reported. An Ar+-laser beam is employed to modulate a second He–Ne laser. The highest frequency achieved was 1.5 × 103 pulses per second with input modulating powers smaller than 10 mW. A homeotropic N-(p-methoxybenzylidene)-p-butylaniline liquid-crystal cell was employed as the nonlinear medium

Arbitrary vortex arrays realized from optical winding of frustrated chiral liquid crystals

We report on the realization of on-demand reconfigurable arbitrary arrays of microscopic optical vortex generators in chiral liquid crystals. These generators are optically inscribed in frustrated cholesteric films by means of the laser-induced local winding of the chiral liquid crystal mesophase. This leads to the storage of microscopic, metastable, topological defect structures endowed with space-variant birefringent properties. Such structures are shown to produce optical vortices with a well-defined orbital state as a result of a spin-to-orbital angular momentum conversion process