Ultra-high Q even eigenmode resonance in terahertz metamaterials

Abstract

We report the simultaneous excitation of the odd and the even eigenmode resonances in a periodic array of square split-ring resonators, with four resonators per unit cell. When the electric field is parallel to their gaps, only the two well-studied odd eigenmodes are excited. As the resonators are rotated relative to one another, we observe the emergence and excitation of an extremely sharp even eigenmode. In uncoupled split-ring resonators, this even eigenmode is typically radiative in nature with a broad resonance linewidth and low Q-factor. However, in our coupled system, for specific range of rotation angles, our simulations revealed a remarkably high quality factor (Q 100) for this eigenmode, which has sub-radiant characteristics. This type of quad-supercell metamaterial offers the advantage of enabling access to all the three distinct resonance features of the split-ring resonator, which consists of two odd eigenmodes in addition to the high-Q even eigenmode, which could be exploited for high performance multiband filters and absorbers. The high Q even eigenmode could find applications in designing label free bio-sensors and for studying the enhanced light matter interaction effects. V

Displacement Current Mediated Resonances in Terahertz Metamaterials

“…Similarly, the decrease in permittivity ( ε ) of materials between the nanogaps enhances the Q-factor of the nanopillar-based SRRs ( 3 c) because a decrease in the permittivity ( ε ) of the nanogap reduces the capacitance ( C ), leading to more energy stored ( U ) in SRRs. [ 25 ] However, asymmetric SRRs and coupled SRR units always contain multiple splits with large split sizes, which are not suitable for biological and biomedical sensing given the small size of biological species. The transmission spectrum of the nanopillar-based SRR and Q-factor calculation is shown in the Supporting Information, Figure S2).…”

“…[21][22][23][24] Another method uses coupling between MMs in a super unit to excite both odd and even modes of the MMs. [ 25 ] The Q-factor of THz MMs needs to be further enhanced (10-20 times) to meet the requirement of ultrasensitive sensors with high selectivity. [ 25 ] The Q-factor of THz MMs needs to be further enhanced (10-20 times) to meet the requirement of ultrasensitive sensors with high selectivity.…”

“…[ 19,20 ] The asymmetric design reduces the radiation loss of the resonator and increases Q-factor up to 30. [ 25 ] The Q-factor of THz MMs needs to be further enhanced (10-20 times) to meet the requirement of ultrasensitive sensors with high selectivity. This approach improves Q-factor by a factor of 5 compared to typical fi lm-based MMs.…”

Alternative design of left-handed metamaterial based on circular resonator and wire strip for waveguide configurations with sensing and absorber applications

“…[18][19][20][21][22][23][24][25][26][27][28][29][30] The simulation process is carried out by locating an FR-4 superstrate, as shown in Fig. The sensing behavior is related with the change in frequency response of S-parameters.…”

“…[9][10][11]18,[20][21][22][23][24][25][26][27][28][29][30][31][32] The sensor application is presented according to the effects of the variations in the size, position, and permittivity of a superstrate layer located in front of the MTM. Since many sensors are based on the interactions between electromagnetic waves and the surroundings, MTMs can also be utilized as sensors.…”