All-dielectric asymmetric planar metasurface based dual-parametric sensor

Abstract

All-dielectric metasurfaces are a rapidly growing area of research because they have lower ohmic losses and sharper resonances than their metallic equivalents. In this work, we have reported a novel all-dielectric metasurface design for dual parameter (refractive index and temperature) sensing applications. The design consists of a square GaAs block on the top of a quartz substrate with a square hole etched on it. An outer cut to the GaAs block is introduced to break the symmetry. The asymmetry enables a sharp Fano resonance mode with 90% spectral contrast and extremely high quality (Q) factor of value 2.8×104 in the near-infrared (NIR) window. The multipolar nature of the high-Q resonance is studied using the cartesian multipolar decomposition technique, which reveals the electric dipolar nature of the resonance. To examine the refractive index capability of the proposed device, we varied the refractive index of the background medium and found that the device is highly sensitive and results in a very high Figure of Merit (FoM) 5384 RIU−1, owing to the very narrow linewidth of the resonance. The same design is also used for temperature sensing, which shows a notable improvement in sensitivity (72.4 pm/∘C) compared to various existing methods available. The in-depth analysis of the resonance in an optimized all-dielectric metasurface and its potential for sensing presented through this paper can be significant in designing high-performance optical sensors.