Non-resonant terahertz field enhancement in periodically arranged nanoslits

Abstract

Ultra-low power electrically reconfigurable magnetoelectric microwave devices J. Appl. Phys. 112, 073915 (2012) Broadband and ultrathin screen with magnetic substrate for microwave reflectivity reduction Appl. Phys. Lett. 101, 154101 (2012) Tunable, narrow-band, all-metallic microwave absorber Appl. Phys. Lett. 101, 141115 (2012) Insertable system for fast turnaround time microwave experiments in a dilution refrigerator Rev. Sci. Instrum. 83, 093904 (2012) Coherent terahertz radiation from high-harmonic component of modulated free-electron beam in a tapered twoasymmetric grating structure Appl. Phys. Lett. 101, 123503 (2012) Additional information on J. Appl. Phys. We analyze ultra strong non-resonant field enhancement of THz field in periodic arrays of nanoslits cut in ultrathin metal films. The main feature of our approach is that the slit size and metal film thickness are several orders of magnitude smaller than the wavelength k of the impinging radiation. Two regimes of operation are found. First, when the grating period P ( k, frequency-independent enhancement is observed, accompanied by a very high transmission approaching unity. With high accuracy, this enhancement equals the ratio of P to the slit width w. Second, when the grating period approaches the THz wavelength but before entering the Raleigh-Wood anomaly, the field enhancement in nanoslit stays close to that in a single isolated slit, i.e., the well-known inversefrequency dependence. Both regimes are non-resonant and thus extremely broadband for P < k. The results are obtained by the microscopic Drude-Lorentz model taking into account retardation processes in the metal film and validated by the finite difference frequency domain method. We expect sensor and modulation applications of the predicted giant broadband field enhancement.

Optimizing Broadband Terahertz Modulation with Hybrid Graphene/Metasurface Structures

“…Such THz metasurfaces were proposed theoretically 29 and show close to unity THz transmission over a broad frequency range. The large transmission arises from the coherent radiation of greatly enhanced in-plane local field in the slits, which efficiently couples to graphene.…”

“…29,31 Remarkably, THz transmission of the metasurface device is also strongly polarization dependent. The transmission for the 4−20 μm device is at maximum when the polarization of light is perpendicular to the slit and at minimum when the polarization is parallel to the slit.…”

Grating-based guided-mode resonance devices and degradation of their performance in real-life conditions

“…3 (a) summarizes the main rules of FDFD calculations which were obtained in the course of working on this paper and manuscripts. 36,37 We see that in our case of transmission calculation it is important to have the domain big enough whereas very fine discretization is not that important. Fig.…”

Nonresonant 104 Terahertz Field Enhancement with 5-nm Slits

“…In THz field transmission, field enhancements of several orders of magnitude have been obtained with a nanometre-wide slit222324. Previously, we have demonstrated enhancement factors of nearly three orders of magnitude with a 70-nm-wide slit21.…”