Ultrasensitive dual-band terahertz sensing with metamaterial perfect absorber

Due to the weak energy storage characteristics of the monolayer metamaterial, how to increase the sub-wavelength scale interaction between biological or chemical samples and terahertz wave on sufficient sensitivity premise becomes the key scientific problems in the study of terahertz sensing technology. In this paper, an ultrasensitive dual-band spectral terahertz sensor with polarization insensitive metamaterial perfect absorber (MPA) is demonstrated. A double-ring shaped metal microstructure integrated with microfluidic channel is applied in the polarization sensitive terahertz sensor. The numerical results show that the normalized sensitivity of refractive index unit 0.638/RIU with mode A and 0.582/RIU with mode B are obtained at 1.04THz and 0.506THz, respectively. The absorptive sensing mechanism is elucidated by the electric field and surface current distributions. Compared to other metamaterials (MMs) based terahertz sensors, the proposed MPA sensor with significantly confined field, enhanced sensitivity and polarization insensitivity is much more suitable for label-free terahertz probing of fluidic matter detection.