Tutorial on broadband transmissive metasurfaces for wavefront and polarization control of terahertz waves

摘要

In order to harness the capabilities of terahertz waves, various metasurface-based functional devices have been developed recently. However, due to the limited usage of systematic optimization methodologies, many existing designs leave room for further bandwidth and efficiency improvement. This article provides an overview on the bandwidth limiting factors associated with metasurfaces and gives a tutorial on a semi-analytical approach to broadband design. The broadband approach incorporates network analysis and genetic algorithm to determine the frequency-independent optimal circuit parameters for multi-layer transmissive metasurfaces, so that targeted complex transmission coefficients can be achieved over a wide bandwidth. The broadband design approach is enabling the configuration and optimization of diverse metasurfaces for wavefront and polarization control of terahertz waves, including quarter- and half-waveplates.