  Optical vortices, as a kind of structured beam with helical phase wavefronts
and doughnut shape intensity distribution, have been used for fabricating
chiral structures in metal and spiral patterns in anisotropic
polarization-dependent azobenzene polymer. However, in isotropic polymer, the
fabricated microstructures are typically confined to non-chiral cylindrical
geometry due to two-dimensional doughnut intensity profile of optical vortices.
Here we develop a powerful strategy for realizing chiral microstructures in
isotropic material by coaxial interference of a vortex beam and a plane wave,
which produces three-dimensional (3D) spiral optical fields. This coaxial
interference beams are creatively produced by designing the contrivable
holograms consisting of azimuthal phase and equiphase loaded on liquid-crystal
spatial light modulator. Then, in isotropic polymer, 3D chiral microstructures
are achieved under illumination of the coaxial interference femtosecond laser
beams with their chirality controlled by the topological charge. Our further
investigation reveals that the spiral lobes and chirality are caused by the
interfering patterns and helical phase wavefronts, respectively. This technique
is simple, stable, and easy-operation, and offers broad applications in optical
tweezers, optical communications and fast metamaterial fabrication.
