Controllable transport of nanoparticles along waveguides by spin-orbit coupling of light

Waveguide optical tweezers can capture and transport nanoparticles, and have important applications in biology, physics, and materials science. However, traditional waveguide optical tweezers need to couple incident light into one end of the waveguide, which causes problems such as difficulty in alignment and low efficiency. Here, we propose a new type of waveguide optical tweezers based on spin-orbit coupling of light. Under the effect of spin-orbit coupling between the waveguide and nearby particles illuminated by a circularly polarized light, the particles experience a lateral recoil force and a strong optical gradient force, which make particles in a large area to be trapped near the waveguide and then transmitted along the waveguide, avoiding the coupling of light into one end of the waveguide. We further demonstrate that the particles can be transmitted along a curved waveguide and even rotated along a ring-shaped waveguide, and its transmission direction can be simply switched by adjusting the spin polarization of incident light. This work has significance in the research of optical on-chip nano-tweezers. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This work introduces a new type of waveguide optical tweezers based on spin-orbit coupling of light, which can solve the problem of difficulty in alignment and low efficiency of traditional waveguide optical tweezers. By utilizing the spin-orbit coupling effect, particles can be transmitted along the waveguide, and the transmission direction can be easily switched by adjusting the spin polarization of incident light.