# Reprogrammable Graphene-based Metasurface Mirror with Adaptive Focal Point for THz Imaging

## TL;DR

This paper introduces a reprogrammable graphene-based metasurface mirror capable of dynamically focusing terahertz waves at arbitrary points, enhancing reconfigurability for imaging and communication applications.

## Contribution

The work presents a novel reconfigurable metasurface design using graphene and coding techniques to achieve adaptive focusing in the terahertz regime.

## Key findings

- Operates near diffraction limit with high focus accuracy
- Offers a wide focusing range with low error
- Enables reconfigurable terahertz imaging and communication systems

## Abstract

Recent emergence of metasurfaces has enabled the development of ultra-thin flat optical components through different wavefront shaping techniques at various wavelengths. However, due to the non-adaptive nature of conventional metasurfaces, the focal point of the resulting optics needs to be fixed at the design stage, thus severely limiting its reconfigurability and applicability. In this paper, we aim to overcome such constraint by presenting a flat reflective component that can be reprogrammed to focus terahertz waves at a desired point in the near-field region. To this end, we first propose a graphene-based unit cell with phase reconfigurability, and then employ the coding metasurface approach to draw the phase profile required to set the focus on the target point. Our results show that the proposed component can operate close to the diffraction limit with high focusing range and low focusing error. We also demonstrate that, through appropriate automation, the reprogrammability of the metamirror could be leveraged to develop compact terahertz scanning and imaging systems, as well as novel reconfigurable components for terahertz wireless communications.