Near-infrared plasma cavity metasurface with independently tunable double Fano resonances

We report a metasurface device based on nano metal-dielectric-metal plasmon cavity arrays. Investigation of the proposed device indicates the sharp absorption peak of double Fano resonance and multiple periods of time-domain oscillations caused by the three-dimensional double resonance. By adjusting the structure parameters, different absorption patterns can be regulated independently with high degree of freedom. The metasurface exhibits sensitive behavior to the environmental refractive index and possesses the sensitivity of 667 nm RIU−1 as a refractive index sensor in the mid-near infrared band, which can be further considered for glucose or temperature sensing.