Simultaneous integration of pattern, frequency and polarization diversities in broadband programmable metasurface for computational imaging

The field diversity of a metasurface stands out as a crucial figure of merit for computational imaging. Conventional techniques typically leverage either pattern diversity through a programmable metasurface or frequency diversity due to dispersion response to enhance sensing capacity. Simultaneously employing pattern diversity and frequency diversity in programmable systems remains highly challenging and currently unattainable, primarily due to the absence of a broadband programmable metasurface. This paper proposes a 1-bit broadband programmable metasurface, enabling the simultaneous utilization of pattern diversity and frequency diversity to tackle this difficulty for computational imaging. The proposed programmable metasurface has a 1-bit phase response (corresponding to 0° and 180°) for each unit cell, which works from 15.5 GHz to 27.5 GHz (corresponding to 55.8% relative bandwidth). A computational imaging system is subsequently implemented using the designed metasurface and field-programmable gate array (FPGA) control board. The experimental results demonstrate that the implemented imaging system has significantly enhanced sensing capacity, thanks to the simultaneous utilization of pattern diversity and frequency diversity. Furthermore, we incorporate polarization to further improve the image quality for polarization-sensitive targets by a 90° rotation of the metasurface system and modification of the control coding. © 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.