Tailor the functionalities of metasurfaces: From perfect absorption to phase modulation

TL;DR

This paper develops a phase diagram based on coupled-mode theory to control and design metasurfaces with functionalities like perfect absorption and phase modulation, validated through experiments and simulations.

Contribution

It introduces a complete phase diagram linking metasurface parameters to functionalities, enabling tailored design of photonic devices.

Findings

The phase diagram predicts metasurface functionalities based on losses.

Experimental tuning switches device functionalities across phase boundaries.

Design guidelines for tunable metasurfaces in the Terahertz regime.

Abstract

Metasurfaces in metal/insulator/metal configuration have recently been widely used in photonics research, with applications ranging from perfect absorption to phase modulation, but why and when such structures can realize what kind of functionalities are not yet fully understood. Here, based on a coupled-mode theory analysis, we establish a complete phase diagram in which the optical properties of such systems are fully controlled by two simple parameters (i.e., the intrinsic and radiation losses), which are in turn dictated by the geometrical/material parameters of the underlying structures. Such a phase diagram can greatly facilitate the design of appropriate metasurfaces with tailored functionalities (e.g., perfect absorption, phase modulator, electric/magnetic reflector, etc.), demonstrated by our experiments and simulations in the Terahertz regime. In particular, our experiments show that, through appropriate structural/material tuning, the device can be switched across the functionality phase boundaries yielding dramatic changes in optical responses. Our discoveries lay a solid basis for realizing functional and tunable photonic devices with such structures.