Physics-informed Inverse Design of Multi-bit Programmable Metasurfaces

TL;DR

This paper introduces a physics-informed inverse design method for multi-bit programmable metasurfaces, enabling enhanced phase tuning and beam steering in terahertz applications through improved accuracy and physical insight.

Contribution

The authors develop a novel physics-informed inverse design approach integrating modified coupled mode theory with neural networks, significantly improving design accuracy and physical understanding of metasurfaces.

Findings

Achieved phase tuning up to 300 degrees without reducing reflection intensity.

Demonstrated beam steering with deflection angles up to 68 degrees.

Validated the design experimentally across multiple coding schemes.

Abstract

Emerging reconfigurable metasurfaces offer various possibilities in programmatically manipulating electromagnetic waves across spatial, spectral, and temporal domains, showcasing great potential for enhancing terahertz applications. However, they are hindered by limited tunability, particularly evident in relatively small phase tuning over 270o, due to the design constraints with time-intensive forward design methodologies. Here, we demonstrate a multi-bit programmable metasurface capable of terahertz beam steering, facilitated by a developed physics-informed inverse design (PIID) approach. Through integrating a modified coupled mode theory (MCMT) into residual neural networks, our PIID algorithm not only significantly increases the design accuracy compared to conventional neural networks but also elucidates the intricate physical relations between the geometry and the modes. Without decreasing the reflection intensity, our method achieves the enhanced phase tuning as large as 300o. Additionally, we experimentally validate the inverse designed programmable beam steering metasurface, which is adaptable across 1-bit, 2-bit, and tri-state coding schemes, yielding a deflection angle up to 68o and broadened steering coverage. Our demonstration provides a promising pathway for rapidly exploring advanced metasurface devices, with potentially great impact on communication and imaging technologies.