Hybridization of optical plasmonics with terahertz metamaterials to create multi-spectral filters

Abstract

Multi-spectral imaging systems typically require the cumbersome integration of disparate filtering materials in order to work simultaneously in multiple spectral regions. We show for the first time how a single nano-patterned metal film can be used to filter multi-spectral content from the visible, near infrared and terahertz bands by hybridizing plasmonics and metamaterials. Plasmonic structures are well-suited to the visible band owing to the resonant dielectric properties of metals, whereas metamaterials are preferable at terahertz frequencies where metal conductivity is high. We present the simulated and experimental characteristics of our new hybrid synthetic multi-spectral material filters and demonstrate the independence of the metamaterial and plasmonic responses with respect to each other. 4755-4767 (1995). 40. M. Naftaly and R. E. Miles, "Terahertz time-domain spectroscopy of silicate glasses and the relationship to material properties," J.

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

“…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.…”

“…Filters fabricated into a metal layer as part of the CMOS process offer a solution to substantial cross-talk between different colours that is expected as CMOS imagers scale to smaller sizes [18]. It is also possible to extend the operation of plasmonic filters to MIR wavelengths by further scaling of the hole size and period [9,10].…”

Multi‐Spectral Materials: Hybridisation of Optical Plasmonic Filters and a Terahertz Metamaterial Absorber

“…[ 21,22 ] It is also possible to extend the operation of plasmonic fi lters to near IR (NIR) wavelengths by further scaling of the hole size and period. [ 11 ] At THz frequencies the plasmonic response is diminished due to the high conductivity of the metal, however, a MM with a specifi c unit cell geometry can still exhibit resonant behaviour. [23][24][25][26] A MM absorber consists of a metal ground plane and an electric ring resonator (ERR) array, separated by a dielectric spacer.…”

“…However, it is possible to consider the ground plane of the SMM as an unperforated metal fi lm at THz frequencies. [ 11 ] Optimisation of the entire SMM was performed by independently simulating the plasmonic fi lters and the MM absorber, with an unperforated ground plane. Details of the simulation procedures are outlined in the experimental section.…”