Loss-induced performance limits of all-dielectric metasurfaces for terahertz sensing

TL;DR

This paper investigates how material losses in all-dielectric metasurfaces affect their performance as terahertz sensors, revealing that even low losses significantly limit their quality factors and sensing capabilities compared to alternative structures.

Contribution

The study provides a realistic analysis of loss effects in all-dielectric metasurfaces and compares their sensing performance with structures supporting extraordinary optical transmission.

Findings

Material losses severely limit the quality factor of all-dielectric metasurfaces.

Performance of all-dielectric metasurfaces can be surpassed by structures with extraordinary optical transmission.

Loss considerations are critical for designing effective THz sensors using metasurfaces.

Abstract

Metasurfaces providing resonances arising from quasi-bound states in the continuum have been proposed as sensors in the THz band due to the existence of strong resonances characterized by high quality factors. Controlling geometrical parameters, the quality factor can be adjusted and, theoretically, designed at will. However, losses in materials critically bound the metasurface performance and limit the quality factor of the resonances. For this reason, all-dielectric metasurfaces have been proposed as an alternative to metal-dielectric structures to reduce losses and achieve extreme functionalities. When implemented by low-loss materials, these structures are usually considered lossless and proposed as ultrasensitive sensors in the THz band. In this paper, we examine the effect of losses in all-dielectric metasurfaces considering realistic materials and study the limitations in the quality factor. In addition, we compare the performance of these structures as sensors with a nanostructure supporting extraordinary optical transmission. Our results show that material loss, even in low-loss materials, severely limits the sensing performance in all-dielectric metasurfaces, and that their performance can be surpassed by structures supporting extraordinary optical transmission.