Accurate encoding of arbitrary complex fields with amplitude-only liquid crystal spatial light modulators

Author(s): Victor Arrizón, Guadalupe Méndez, and David Sánchez-de-La-Llave

Abstract:

“We show that computer generated holograms, implemented with amplitude-only liquid crystal spatial light modulators, allow the synthesis of fully complex fields with high accuracy. Our main discussion considers modified amplitude holograms whose transmittance is obtained by adding an appropriate bias function to the real cosine computer hologram of the encoded signal. We first propose a bias function, given by a soft envelope of the signal modulus, which is appropriate for perfect amplitude modulators. We also consider a second bias term, given by a constant function, which results appropriate for modulators whose amplitude transmittance is coupled with a linear phase modulation. The influence of the finite pixel size of the spatial light modulator is compensated by digital pre-filtering of the encoded complex signal. The performance of the discussed amplitude CGHs is illustrated by means of numerical simulations and the experimental synthesis of high order Bessel beams.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 20, pp. 7913-7927, 2005
DOI: 10.1364/OPEX.13.007913

Fractional optical vortex beam induced rotation of particles

Author(s): S. Tao, X-C. Yuan, J. Lin, X. Peng, and H. Niu

Abstract:

“We experimentally demonstrate optical rotation and manipulation of microscopic particles by use of optical vortex beams with fractional topological charges, namely fractional optical vortex beams, which are coupled in an optical tweezers system. Like the vortex beams with integer topological charges, the fractional optical vortex beams are also capable of rotating particles induced by the transfer of orbital angular momentum. However, the unique radial opening (low-intensity gap) in the intensity ring encompassing the dark core, due to the fractional nature of the beam, hinders the rotation significantly. The fractional vortex beams orbital angular momentum and radial opening are exploited to guide and transport microscopic particles.”

Link to Publications Page

Publication: Optics Express
Issue/Year: Optics Express, Vol. 13, Issue 20, pp. 7726-7731, 2005
DOI: 10.1364/OPEX.13.007726