Temperature Tunable Multiple Ultraviolet to Near-Infrared Perfect Absorption as Highly Sensitive Metamaterial Biosensor

Realizing tunable multiband perfect absorption from ultraviolet (UV) to near-infrared (IR) range in nanophotonics and metamaterials is extremely significant for solar energy harvesting and optical sensors. Here, five narrowband and broadband perfect absorbers (PA) are simultaneously achieved in a simple 3-D metamaterial consisting of aluminum (Al) standing U-shaped split-ring resonators (SUSRRs) on SiO2/Al layer, which stems from the plasmonic hybridization between three high-order surface plasmon polarization (SPPs) and multiple localized surface plasmon (LSPs) localized both within the individual SUSRR as well as within the dielectric layer underneath the SUSRR. These penta-band perfect absorption peaks can be tuned by varying the temperature of the sealed ethanol with a temperature tuning performance of 0.331 nm/°C. Due to the two narrow perfect absorption at 473 and 157 nm being sensitive to the surroundings, our proposed Al SUSRR array as a high-sensitivity biosensor displays the ultra-large figure of merit (FoM $^{\ast} $ ) of $3.0\times104$ and $1.55\times104$ , which could be applied to gas sensing and the detection of the sub-nanometer thickness of analyte film.