title: Helico-conical optical beams: a product of helical and conical phase fronts.
abstract: Helico-conical optical beams, different from higher-order Bessel beams, are generated with a parallel-aligned nematic liquid crystal spatial light modulator (SLM) by multiplying helical and conical phase functions leading to a nonseparable radial and azimuthal phase dependence. The intensity distributions of the focused beams are explored in two- and threedimensions. In contrast to the ring shape formed by a focused optical vortex, a helico-conical beam produces a spiral intensity distribution at the focal plane. Simple scaling relationships are found between observed spiral geometry and initial phase distributions. Observations near the focal plane further reveal a cork-screw intensity distribution around the propagation axis. These light distributions, and variations upon them, may find use for optical trapping and manipulation of mesoscopic particles.
authors.forename: Carlo
authors.initials: C
authors.lastname: Alonzo
authors.forename: Peter John
authors.initials: PJ
authors.lastname: Rodrigo
authors.forename: Jesper
authors.initials: J
authors.lastname: Glückstad