Standard multiple-beam holography has been largely used to produce gratings in polymer-liquid crystal composites, like POLICRYPS, H-PDLC gratings and POLIPHEM [1]. In this work we present a different approach to liquid crystalpolymeric grating produc
tion, based on the Computer-Generated Holography (CGH). The great advantage of using CGH is that interferometer-based schemes are no longer necessary, avoiding problems related to long term stability of the interference pattern and multi-beam complex optical setup. Moreover, the CGH technique allows a wider choice of pattern designs. In this preliminary work, we obtained promising results, as for instance the patterning of a square-wave refractive index modulation of a LCpolymeric composite, a pattern which is not achievable with standard two-beam holography.
We studied a novel family of paraxial laser beams forming an overcomplete yet nonorthogonal set of modes. These modes have a singular phase profile and are eigenfunctions of the photon orbital angular momentum. The intensity profile is characterized
by a single brilliant ring with the singularity at its center, where the field amplitude vanishes. The complex amplitude is proportional to the degenerate (confluent) hypergeometric function, and therefore we term such beams hypergeometric gaussian (HyGG) modes. Unlike the recently introduced hypergeometric modes (Opt. Lett. {textbf 32}, 742 (2007)), the HyGG modes carry a finite power and have been generated in this work with a liquid-crystal spatial light modulator. We briefly consider some sub-families of the HyGG modes as the modified Bessel Gaussian modes, the modified exponential Gaussian modes and the modified Laguerre-Gaussian modes.
