Terahertz high-Q magnetic dipole resonance induced by coherent Fano interactions

Abstract

High Q-factor resonance holds great promise for bio-chemical sensing and enhanced light–matter interaction. However, terahertz (THz) magnetic resonances usually demonstrate low Q-factors, resulting in huge energy radiation loss particularly in high frequency bands. Here, we show that high Q-factor magnetic dipole resonance at THz frequencies can be achieved by exploiting the coherent Fano interactions with strong field enhancements in an array composed of single metallic split-ring resonators, working at Wood–Rayleigh anomalies. It can give rise to ultrahigh Q-factor beyond 104 in the THz regime. Experimentally, the measured Q-factor of dominant magnetic dipole resonance can achieve no less than a level of ∼261 by Lorentzian fitting to the experimental data. In addition, a high Q-factor of the fundamental-order magnetic dipole resonance is demonstrated beyond 30. High- Q magnetic dipole resonance is closely associated with ultralow-damping and negative permeability in the THz band. The measurements of magnetic dipole resonances are in good agreement with the theoretical analyses. Our scheme suggests a feasible route to suppress radiative loss for enhanced THz field-matter interaction.

High-Q transmission characteristics in terahertz guided-mode magnetic resonance system

“…Periodic boundary conditions in both x and y directions along with perfectly matched layer is the z direction are applied to the metamaterial unit cell. Theoretical simulation techniques can be supported in recent papers [21,22,31]. The filtering properties of the resonator can occur normally when an infinite metasurface is fabricated into a finite sample [21,22,31].…”

“…Theoretical simulation techniques can be supported in recent papers [21,22,31]. The filtering properties of the resonator can occur normally when an infinite metasurface is fabricated into a finite sample [21,22,31]. The relative permittivity of gold is calculated by the Drude model as ε = 1-ω p 2 /(ω 2 +iγ c ω) in the THz regime, with plasma frequency ω p = 1.37 × 10 16 rad/s and damping rate γ c = 4.08 × 10 13 rad/s [22,32,33].…”

“…The metals have excellent conductivity at THz frequencies, the ohmic losses of most metallic metamaterials are relatively quite low. The quartz substrate is taken as a lossless dielectric with relative electrical permittivity of 2.14 [31]. The plane waves are incident normally to the unit cell along the z direction with the x-polarization (perpendicular to the gap of SRRs).…”

Application of multi-objective optimization genetic algorithm to design terahertz metamaterials with fano resonances

“…This resonant behavior offers potential applications in various fields, including sensing, optical filtering, and nonlinear optics. Previous studies have indicated that the geometric parameters of the unit structure influence the Fano resonance [4][5][6][7]. Thus, the optimum design of these unit structures plays a crucial role in both generating and modulating the Fano resonance.…”

Ultra-high Q-factor and amplitude-tunable Fano resonance in vanadium dioxide–silicon hybrid metamaterials

“…[10][11][12] Enhanced manipulation of terahertz waves and the response of their elds to matter is possible by combining multiple materials and designing different cell structures. 13 Metamaterial-excited Fano resonance has become an important research direction. [14][15][16][17] With the development of tunable materials, such as graphene and VO 2 , multifunctional sensors based on metamaterials have progressed signicantly.…”