Wavefront Engineering With Reconfigurable Intelligent Surfaces for Improved Sensing Capabilities in The THz Band

The terahertz (THz) band offers the advantages of mas-sive available bandwidth and small signal wavelengths with revolutionary potential in both communication and sensing applications. However, the increased noise power from the larger bandwidth, as well as the increased path losses due to smaller wavelengths severely restrict the signal-to-noise ratio (SNR). In this light, reconfigurable intelligent surfaces (RISs) have been proposed as breakthrough devices that can be readily scaled up to create high-gain aperture systems, which are likely to have near-field applications. Here, wavefronts specifically engineered within the near field provide opportunities for improved sensing capabilities. Specifically, in this paper, we highlight how the greater depth of focus through Bessel beams can be utilized to improve the resolution capability of THz-band sensing. We numerically derive and show that Bessel beams can help improve target classification due to increased SNR in detection and increase resolution through increased bandwidth exploitation as well.