Tailoring Terahertz Near-Field Enhancement via Two-Dimensional Plasmons

Abstract

We suggest a novel possibility for electrically tunable terahertz near-field enhancement in flatland electronic materials supporting two-dimensional plasmons, including recently discovered graphene. We employ electric-field effect modulation of electron density in such materials and induce a periodic plasmonic lattice with a defect cavity. We demonstrate that the plasmons resonantly excited in such a periodic plasmonic lattice by an incident terahertz radiation can strongly pump the cavity plasmon modes leading to a deep subwavelength concentration of terahertz energy, beyond λ/1000, with giant electric-field enhancement factors up to 10(4), which is 2 orders of magnitude higher than achieved previously in metal-based terahertz field concentrators.

Transmission line theory of collective plasma excitations in periodic two-dimensional electron systems: Finite plasmonic crystals and Tamm states

“…Plasmonic Tamm states in these various material systems have special potential when applied for the field enhancement they can produce at the crystal boundary. Similar to the effect of a plasmonic crystal defect [55], the Tamm state can be harnessed for its strong near-field enhancement in combination with the sub-wavelength nature of the 2D plasmon. For example, the Tamm state could be coupled to an adjacent detection element [56].…”

Inducing an Incipient Terahertz Finite Plasmonic Crystal in Coupled Two Dimensional Plasmonic Cavities

“…Two dimensional (2D) THz plasmons in silicon (Si) [4], III-V materials such as GaAs/AlGaAs [5] and GaN/AlGaN [6] heterostructures, and graphene [7,8] similarly are sub-wavelength compared to free-space electromagnetic waves, but have an additional degree of freedom due to the ability to control electron density, and thus the 2D plasma frequency, through a field effect. It is this latter capability that has generated interest in 2D plasmonic devices [9,10] such as THz detectors [11][12][13][14], mixers [15,16], emitters [17,18], and field enhancement structures [19].…”

“…This pairing of modes is indicative of a plasmonic band structure forming in this system. In a strongly modulated regime, low frequency plasmons should be mostly localized in the regions with low electron density, the sub-cavities below G1 and G2 [19]. Thus, the mode pairing may be viewed as the energetic splitting of the degenerate eigenmodes in these subcavities due to coherent coupling between them.…”

Proposal of multiple-slot silica high-mesa waveguide for infrared absorption

“…This is because multiple-slot high-mesa structures comprise several parallel conventional single high-mesas adjacent to each other, and the slot width between mesas is only of the order of nanometers. Thus, the near-field effect enhances the optical power portion inside the slot region [19], and higher Γ air can be expected from the multiple structure. The optical fields were simulated using the finite element method (FEM).…”