Optical vortex possesses an on-axial phase singularity and an orbital angular momentum (OAM) due to its spiral wavefront characterized by a topological charge ℓ. OAM of the optical vortex can twist or spin the target materials, such as silicon, metal, and polymer, to form chiral structures.
In this paper, we report on the creation of helical microfibers by irradiating picosecond optical vortex pulses with a wavelength of 532 nm to ultraviolet curing resin via a two-photon-absorption photopolymerization process.
Self-focusing effect of incident vortex pulses, arising from the photo-polymerization, confines efficiently optical vortex field to form a self-written helical fiber waveguide with the help of OAM transfer effect.
The resulting helical microfibers exhibited a length of ~300 μm Also, we could control the twisted direction of fibers merely by changing the sign of the topological charge of optical vortex. These experiments will open up a new way to the practical application of helical microfiber to optical communications.
We demonstrate a self-written sub-millimeter (>300 μm) helical fiber in a photo-cure resin by irradiation of non-diffractive 1st-order Bessel beam with an orbital angular momentum. The twisted direction of the helical fiber can be controlled by only reversing the sign of the topological charge of Bessel beam.