A Novel Subwavelength Microbolometer for Terahertz Sensing

Abstract

A subwavelength aperture-microbolometer sensor was simulated using a finite-difference time domain (FDTD) numerical method. The system consisted of a focusing bullseye grating with a central subwavelength aperture. A thin vanadium oxide sensing layer was suspended behind the aperture for sensing purposes, backed by a thin layer of silicon dioxide. The maximum electric field across the vanadium oxide was measured as a function of incident field. Total noise equivalent power (NEP) was estimated to be 180 pW/√Hz at a frequency of 0.665 THz, comparable to similar current micro sensors. The formation of surface plasmonics greatly increases its sensitivity to particular incident wavelengths. This fact, along with its compact size, make this system a promising candidate for numerous low-cost, small-scale terahertz sensing applications.

Surface plasmon-assisted terahertz imaging array

“…Recently, this bulls eye structure was paired with a microbolometer for the sensing of terahertz electromagnetic waves [8]. Here the vanadium bolometer sensor was replaced with a metamaterial-inspired structure tuned to the plasmonic frequency of the bulls eye [23,24].…”

“…A coupled subwavelength aperture-microbolometer system was previously proposed and simulated [8]. It was theoretically shown that spoof surface plasmon structure can be used to strongly confine field on top of a bolometer structure to enhance sensitivity.…”

Breaking Bullseye’s Symmetry for Axial Field Focusing

“…The higher transmission than the one expected from Bethe's theory [2] is related to the coupling of surface plasmon polariton which confines electromagnetic energy around the aperture. This field enhancement, first observed in optical regime [3] then in the THz and microwave range [4,5], leads to possible applications like near field imaging [6,7], high gain antenna [8,9], waveguide coupler-decoupler [10] and chemical sen-D. Armand ( ) · T. Tanaka Japan Science and Technology Agency, CREST, Kawaguchi, 332-0012, Japan e-mail: damien.armand@gmail.com sors. In order to enhance the field even more, such special designs at the center of the bullseye were proposed as the resonant element [11], the bowties [12] and the Siemens-star [13] shape.…”