# Energy‐Controllable Manipulation on Surface Waves and Propagating Waves by Bifunctional Metasurfaces

## TL;DR

This paper introduces a metasurface that can control both surface and propagating waves using a single device, enabling compact and efficient integrated optics.

## Contribution

A bifunctional metasurface is proposed to simultaneously manipulate surface and propagating waves using resonance and geometric phases.

## Key findings

- Microwave metadevices were experimentally realized to convert left circularly polarized beams into desired propagating and surface wavefronts.
- Energy distribution between output channels can be tailored through numerical design.
- The metasurface enables control of both far- and near-field electromagnetic waves using a single platform.

## Abstract

Manipulating propagating waves (PWs) and surface waves (SWs) in desired manners is important in photonics, but controlling these two electromagnetic modes usually requires separate devices, which is unfavorable for integration optics applications. Recently, although metasurfaces capable of controlling both PWs and SWs have been proposed, they typically rely on dynamically varying the helicities of incident circularly polarized (CP) light, causing complexities in practical applications. In this work, we propose an alternative scheme for designing metasurfaces encoded with both resonance and geometric phases that can simultaneously control PWs and SWs through the co‐ and cross‐polarized output channels under the excitation of a CP wave with a particular helicity. We experimentally prove this concept by realizing two microwave metadevices that can convert normally incident beams with left circular polarization (LCP) into PWs and SWs with predetermined wavefronts. Additionally, we numerically demonstrate how to design metadevices with predetermined energy distributions within these two functional output channels. Our work paves the road to tailor both far‐ and near‐field electromagnetic waves using a single ultra‐compact platform, which can find many applications in integrated optics.

This work presents a bifunctional metasurface for the simultaneous control of propagating and surface waves under the excitation of a circularly polarized wave with a particular helicity. It merges resonance and geometric phases to route wavefronts through distinct channels, validated via microwave experiments. The design also enables tailored energy distribution between channels, offering a compact multifunctional platform for integrated photonics.