Multispectral metamaterial absorber

Abstract

We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 μm. This resonance is in addition to the THz metamaterial absorption resonance at 109 μm (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging.

Multi-spectral materials: hybridisation of optical plasmonic filters, a mid infrared metamaterial absorber and a terahertz metamaterial absorber

“…As an example, when PECVD SiO 2 is used as the insulating layer, at 2 THz the required thickness to obtain 100% absorption is 2 μm however at IR frequencies, e.g. 4 μm, the insulator thickness is only 50 nm [7]. The plasmonic filters require a SiO 2 cap layer thicker than the metal film thickness in order to match the SiO 2 -Al modes on both sides of the metal film and therefore maximise the transmission through the filter [13].…”

“…The sixteen colour plasmonic filter set was designed by scaling the hole size and the array period to shift the resonant wavelength, whilst maintaining similar bandwidths and transmission magnitudes. The MIR and THz MM absorbers geometries were inspired by established designs [7,25,26]. The fundamental resonant frequency of a MM absorber based on a cross shaped ERR is [32]:…”

“…Synthetic multi-spectral materials (SMMs): structured materials capable of operating over different wavebands simultaneously, offer a way to coaxially filter and absorb visible, IR and THz radiation and therefore offer an attractive alternative to conventional detection methods [6][7][8][9][10]. SMMs exploit hybridised metamaterial and plasmonic structures to combine multi-spectral functionalities into a single material.…”

“…By scaling the plasmonic and MM geometries and selecting the appropriate constituent materials one can realise a universally multifunctional optical material in any waveband from the visible to mm wave. In previous work we have developed SMMs that can: (1) filter visible, near infrared (NIR) and THz [10]; (2) filter visible, NIR and absorb THz [9]; (3) filter visible, NIR and mid IR (MIR) and absorb THz [8] and (4) absorb both MIR and THz [7]. In this paper we demonstrate through simulations and experimentally a SMM capable of filtering 15 visible wavelengths and one NIR wavelength while also absorbing MIR and THz radiation.…”

Design of a concise and dual-band tunable metamaterial absorber

“…In addition, performances of the PMA have been improved significantly. On the one hand, the absorption band changes from a single band to dual band [8][9][10] , multiband [11][12][13][14] , and broadband [15][16][17] . For example, Ma et al proposed a dual-band polarization-insensitive terahertz absorber based on double closed ring [18] , Liu et al demonstrated the broadband absorber by using a multilayer stacked structure [12] , and Shen et al presented a triple-band absorber [13] .…”