Ultra-high sensitivity terahertz sensor based on a five-band absorber

Terahertz sensing is one of the most promising methods for label-free and noninvasive detection of refractive index changes. However, the figure of merit (FOM) of terahertz sensors in practical applications has been low. In this paper, a metamaterial sensor based on simple stacking of gold and silicon dioxide is proposed, through whose structure not only narrow-band absorption with five absorption peaks is realized, but FOM is also improved to 1792. The excellent sensing performance and the mature manufacturing technology of this kind of structure provide a platform for the design of multi-band photodetectors and high-sensitivity sensors.