Work

Transverse‐spin–momentum locking in a single‐crystalline plasmonic gap waveguide with a circular nanohole cavity

Year: 2025

Type: article

Abstract: Transverse spin momentum in optical fields enables spin‐dependent routing of light, offering a promising route toward nonreciprocal and chiral photonic functionalities. Here, we demonstrate robust, polarization‐selective waveguiding in a plasmonic gap waveguide, enhanced by a circular nanohole cavity. Our device is fabricated via focused ion beam milling on single‐crystalline gold flakes, yielding atomically smooth interfaces that minimize scattering losses. Under circularly polarized excitation, the nanohole cavity induces transverse spin, thereby locking the propagation direction of surface plasmons polaritons within the waveguide. Experimental measurements confirm strong directional transmission, closely matching theoretical expectations. These findings highlight the utility of single‐crystalline gold for spin–orbit photonic devices and pave the way for integrated optical isolators and other nonreciprocal elements.

Source: ETRI Journal

DOI: 10.4218/etrij.2025-0169

Authors: Hae‐Seok Jeong, Soon‐Jae Lee

Institutions: Korea University, Electronics and Telecommunications Research Institute

Language: English

Topic: Plasmonic and Surface Plasmon Research

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: diamond

Funders: National Research Foundation, National Research Foundation of Korea, Ministry of Science and ICT, South Korea

Awards: G2815412160, G6705520376, G8881652838