Runqi Jia | Searcharxiv

arXiv2026

Janus Dipoles: Fundamentals, Realizations, and Emerging Applications

The Janus dipole - featuring orthogonally oriented electric and magnetic dipoles with a 90-degree phase difference - has emerged as a powerful paradigm for wave manipulation. Unlike traditional Huygens dipoles used for directional control, this unique configuration exhibits strongly asymmetric, face-selective near-field behavior while maintaining a quasi-isotropic far-field radiation pattern. These remarkable properties make the Janus dipole an essential platform for directional wave shaping, with wide-ranging applications in on-chip photonics, quantum interactions, and wireless power transfer. This review systematically traces the rapid development of the Janus dipole from its foundational theoretical inception to its diverse implementation platforms across optical, microwave, and acoustic frequencies. In this paper, we explore the governing principles, classify realization strategies into passive Janus dipoles, active Janus dipoles, and advanced near-field coupling control, and highlight emerging frontiers. By bridging foundational electrodynamics with advanced device engineering, this paper serves as an essential reference and roadmap for researchers designing next-generation, highly integrated, and compact wave-manipulation systems.

physics.app-ph↗

arXiv2023

Transparent matte surfaces enabled by asymmetric diffusion of white light

The traditional wisdom for achieving transparency is to minimize disordered scattering within and on the surface of materials, so as to avoid translucency. However, the lack of disordered scattering also deprives the possibility of achieving a matte surface, resulting in the specular reflection and glare on transparent materials as a severe light pollution issue. In this work, we propose a solution utilizing optical metasurfaces1-2 to overcome this long-existing dilemma. Our approach leverages an asymmetric background in metasurface design to achieve highly asymmetric diffusion of white light, maximizing diffusion in reflection while minimizing it in transmission across the entire visible spectrum. Using industrial lithography, we have created macroscale transparent matte surfaces with both strong matte appearance and clear transparency, defying the conventional belief that these two optical features are incompatible. These surfaces provide a remarkable phenomenon of switching between transparent or matte appearances via the brightness contrast between the front and rear ambient lights. They also support a unique application in transparent displays and augmented reality, offering perfectly preserved clarity, wide viewing angles, full color, and one-sided displays capabilities. Our findings usher in a new era of optical materials where the desirable properties of both transparent and matte appearances can be seamlessly merged.

physics.optics↗