Optical pipeline: Trapping and guiding of airborne particles

Researchers conducted a study to create new type of a stable trap for controlling absorbing particles in open air using two optical vortex beams. The trap was formed between the focal planes of counterpropagating vortex beams. It was observed that optical vortices created a ring-shaped transverse intensity distribution, and the particles were trapped at the intensity minima. The researchers used clusters of carbon nanoparticles produced by a high-repetition-rate laser ablation with typical sizes between 0.1 and 10 μm, along with hollow glass spheres coated with a carbon layer to increase light absorption, with a size from 10 to 150 μm to demonstrate photophoretic manipulation of aerosols. The trap was converted into an optical pipeline for transporting particles over large distances in gases by retaining only a single vortex beam.