Fan-shaped optical laser beams blow away impurities

Optical tweezers, a subject of research that won the Nobel Prize in Physics in 2018, have extraordinary applications in multi-dimensional optical trapping and particle transportations. When enabled by vortex beams, optical tweezers can control the movement of a microparticle or a cluster of microparticles. However, the use of optical tweezers can be negatively affected by impurities in the fluid surrounding trapped particles or cells.

Wang et al. designed a fan-shaped optical vortex beam that literally blows away the impurities in the surrounding fluid environment.

Using rational phase modulation, the authors assembled three spiral beams, together with a central hollow beam, into a fan-shaped vortex beam based on the well-known conical vortex phase. They experimentally demonstrated the beam’s ability to perform optical clearing, optical shielding and optical transporting.

“Just as an electric fan can blow away the impurities in the air, a fan-shaped optical beam can continuously blow away the impurities in fluid environments of high particle concentrations,” said author Liqin Tang. “The fan blades can blow away particles or impurities, while the fan head can shield or protect a target particle or cell.”

The authors are the first to demonstrate fan-shaped optical vortex beams. These beams have application in an optical tweezer setting as well as in optical trapping and manipulation.

“We hope to refine our design method so that the fan-shaped beam not only can blow away but also attract particles to a target area depending on application needs. The tool can be used more efficiently to separate different kinds of particles or cells, to do large-scale transportation of particles in a microfluidic chip, and to separate and shield a sick cell from biological environment,” said Tang.

Source: “Optical clearing and shielding with fan-shaped vortex beams,” by Haiping Wang, Liqin Tang, Jina Ma, Huiwen Hao, Xiuyan Zheng, Daohong Song, Yi Hu, Yigang Li, and Zhigang Chen, APL Photonics (2019). The article can be accessed at https://doi.org/10.1063/1.5133100 .