Bragg-Mirror-Assisted High-Contrast Plasmonic Interferometers: Concept and Potential in Terahertz Sensing

Abstract

A Bragg-mirror-assisted terahertz (THz) high-contrast and broadband plasmonic interferometer is proposed and theoretically investigated for potential sensing applications. The central microslit couples the incident THz wave into unidirectional surface plasmon polaritons (SPPs) waves travelling to the bilateral Bragg gratings, where they are totally reflected over a wide wavelength range back towards the microslit. The properties of interference between the SPPs waves and transmitted THz wave are highly dependent on the surrounding material, offering a flexible approach for the realization of refractive index (RI) detection. The systematic study reveals that the proposed interferometric sensor possesses wavelength sensitivity as high as 167 μm RIU−1 (RIU: RI unit). More importantly, based on the intensity interrogation method, an ultrahigh Figure-of-Merit (FoM) of 18,750% RIU−1, surpassing that of previous plasmonic sensors, is obtained due to the high-contrast of interference pattern. The results also demonstrated that the proposed sensors are also quite robust against the oblique illumination. It is foreseen the proposed configuration may open up new horizons in developing THz plasmonic sensing platforms and next-generation integrated THz circuits.

Breaking the Symmetry of a Metal–Insulator–Metal-Based Resonator for Sensing Applications

“…As seen, the standing wave occurs in the circularshaped ring resonator, and most input EM wave traps in the circular-shaped ring resonator at λ res . The incident wavelength highly influences the |H| patterns of SPP modes due to the different phase and wave number [44,70]. The light spot number of |H| fields in circularshape ring resonator are two for mode 1 in case 1, two, and four for modes 1-2 in case 2, and two, two, three, four, and five for modes 1-5 in case 3, respectively.…”

Ultra-High Sensitivity Terahertz Microstructured Fiber Biosensor for Diabetes Mellitus and Coronary Heart Disease Marker Detection

“…Compared with traditional electromagnetic waves, the THz wave has been widely used in biochemical sensing because of its low energy, transient absorption, fingerprint region and water absorption properties [ 17 ]. Currently, among terahertz sensing technologies, terahertz time-domain spectroscopy (THz-TDS) [ 21 , 22 ], terahertz surface plasmon resonance (SPR) sensors [ 23 , 24 ], and terahertz surface plasmon polariton (SPP) interferometry sensors [ 25 , 26 ] are very popular among researchers. In particular, the application of THz-TDS, especially in tumor and other disease detection, has attracted much attention, as an emerging nondestructive detection technique.…”