Ultrafast Photoalignment: Recording a Lens in a Nanosecond

Liquid crystals can be photoaligned with a single nanosecond pulse acting on thin photoanisotropic coatings on the cell substrates. This phenomenon was demonstrated for pulses of 532 nm and 355 nm wavelengths (second and the third harmonics of a Nd:YAG laser). Direct printing of liquid crystal cycloidal diffractive waveplates and diffractive waveplate lenses characterized by high spatial frequencies required only a mJ energy. The liquid crystal alignment dynamics reveal a fast component related to photoalignment of molecules within the photoanisotropic layer and a slower component related to alignment of the liquid crystal within the cell.