Optical isolation induced by subwavelength spinning particle via spin-orbit interaction

TL;DR

This paper introduces a compact, magnetic-free optical isolator using a rotating hyperbolic nanoparticle that exploits spin-orbit interaction to achieve high isolation efficiency in the infrared spectrum.

Contribution

It presents a novel mechanism combining hyperbolic metamaterials and spin-orbit interaction for optical isolation at subwavelength scales, overcoming limitations of traditional bulky rotation-based devices.

Findings

Achieves >95% isolation of infrared light

Demonstrates unidirectional coupling via spin-orbit interaction

Operates at feasible rotation speeds for practical applications

Abstract

Optical isolation enables nonreciprocal manipulations of light with broad applications in optical communications. Optical isolation by rotating structures has drawn considerable attention due to its magnetic-free nature and unprecedented performance. Conventional rotation-based optical isolation relies on the use of bulky cavities hindering applications in subwavelength photonics. Here, we propose a novel mechanism of optical isolation by integrating the unique dispersion of a hyperbolic metamaterial with the transverse spin-orbit interaction of evanescent waves. We show that rotation of a subwavelength hyperbolic nanoparticle breaks the time-reversal symmetry and yields two resonant chiral modes that selectively couple to the transverse spin of waveguide modes. Remarkably, the transverse spin-orbit interaction can give rise to unidirectional coupling and $>95\%$ isolation of infrared light at an experimentally feasible rotation speed. Our work fuses the two important fields of optical isolation and photonic spin-orbit interactions, leading to magnetic-free yet compact nonreciprocal devices for novel applications in optical communications, chiral quantum optics, and topological photonics.