Dual high-Q resonance sensing for refractive index and temperature based on all-dielectric asymmetric metasurface

In this work, we present a high-quality (Q) dual-resonance sensor based on all-dielectric metasurface for refractive index and temperature sensing simultaneously. The all-dielectric metasurface was composed of a periodic array of Si nanocluster placed on the commercially available glass substrate. Two distinct optical resonance modes with extremely high Q factors of 13500 and 14900, a magnetic quadrupole mode (MQ), and toroidal dipole mode (TD), are observed at 1614.12 nm, and 1639.02 nm in the reflection spectra, and confirmed by the electromagnetic field distribution of each resonance. To further reveal the underlying coupling effects of the two resonances, we also perform a systematic analysis of the influence of the differences in radius (ΔR) and gap (Δx and Δy). At last, the refractive index and temperature sensing performance were investigated. More specifically, the proposed sensor exhibits a maximum refractive index sensitivity of 418 nm/RIU for the analyte refractive index range between 1.33 and 1.37, and maximum temperature sensitivity of 86.4 pm/°C in the range of 0 °C–40 °C, which demonstrates great linear relationship and is much better than the previous sensors based on all-dielectric structure. The proposed all-dielectric metasurface is an effective way to achieve refractive index and temperature dual-parameter sensing, which will facilitate wide applications in unstable environment, such as the measurement of temperature and salinity in seawater.