Ultra-subwavelength focusing and giant magnetic-field enhancement in a low-loss one-way waveguide based on remanence

TL;DR

This paper introduces a low-loss, remanence-based one-way waveguide that achieves ultra-subwavelength focusing and significantly enhances magnetic fields in the microwave regime, enabling advanced applications in sensing and energy storage.

Contribution

It presents a novel 3D surface magnetoplasmon waveguide utilizing remanence for efficient energy localization without external magnetic fields.

Findings

Achieved five orders of magnitude magnetic field enhancement.

Demonstrated ultra-subwavelength focusing with $ extasciitilde 10^{-4} imes 10^{-4}$ wavelength scale.

Enabled practical 3D applications with low propagation loss.

Abstract

The subwavelength focusing based on surface plasmon polaritons (SPP) has been widely explored in tapered metallic structures. However, the efficiency of energy localization is relatively weak, largely due to high propagation loss and strong back reflection. Here, we propose a straight-tapered 3-dimensional (3D) one-way surface magnetoplasmon (SMP) waveguide with the ending surface of $\sim 10^{-4}\lambda_0 \times 10^{-4}\lambda_0$ to achieve energy focusing in the microwave regime. Due to low propagation loss of SMP, we achieve huge magnetic field enhancement in such an ultra-subwavelength area, by five orders of magnitude. Instead of using an external static magnetic field, our proposed SMP waveguide relies on remanence, which is very convenient for operating practical 3D applications. These results show promising applications in magnetic-field enhancing or quenching fluorescence, luminescence or nonlinearity of 2D materials, novel scanning near-field microwave microscopy and energy storage.