Coulomb interaction mediated tuning of surface plasmon resonances in terahertz hole arrays

Abstract

Resonance excitation of surface plasmons in sub-wavelength periodic apertures (popularly known as hole arrays) is typically decided by its lattice configurations and the constituent material characteristics. Therefore, the excitation frequency of surface plasmon resonances (SPRs) in hole arrays is not easy to alter without modifying these basic structural parameters. However, we experimentally demonstrate modulation of SPR frequency by carefully incorporating an additional hole of similar geometry. By suitably modifying the relative positions between the holes inside the unit cell (fixed lattice parameters), we have tailored the SPR excitation frequency. Predominantly, we attribute such frequency detuning to near-field Coulomb interactions in between the holes that can modify the effective permittivity of the hole arrays, hence SPR characteristics. In totality, our experiments demonstrate a 7.6% shift in the SPR frequency. Further, all the experimental findings are explained through elaborate electromagnetic simulations that helped to acquire deeper physical insights related to the SPR excitation. We believe such near-field effect-based resonance tuning can find potential applications in realizing SPR-based sensors, tunable filters, and tunable non-linear devices operating in the terahertz (THz) domain.

Ultrathin Twisted Stacked Gap‐Plasmon Metasurface with Giant and Tunable Shortwave Infrared Chirality

“…For arrays of subwavelength apertures, the holes are considered inverse antennae capable of controlling the profile of incident electromagnetic waves. [52,53] How the interelement coupling affects the chiroptical performance of a twisted stacked metasurface is yet to be explored systematically. We investigate this in our chiral metasurface by changing the nanohole size in an identical MIM metastructure with the same array periodicity.…”

Sensing of nanoporous 2D materials like r-GO using THz hole arrays

“…Additionally, numerous theoretical models have been developed to elucidate the underlying physics [6]. Since then, EOT-based sensing has emerged as a highly active area of research, with several comprehensive reviews addressing detection in both the visible and infrared domains, as well as in the THz regime [7]- [9]. Moreover, hole arrays in the THz spectrum represent a significant opportunity to advance THz sub-wavelength optics, thus enabling the development of highly sensitive THz sensing and imaging systems [10], [11].…”

Terahertz sensing of reduced graphene oxide nanosheets using sub-wavelength dipole cavities

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