*These authors contributed equally to this work. SUPPORTING INFORMATION:Coupled systems composed of asymmetric resonator elements have symmetric and antisymmetric resonances. In the manuscript, only the antisymmetric resonances are reported for the SRR-bar and ACSRR cases, as the amount of tuning is larger and more strongly dependent on the coupling distance than for the symmetric resonance. In Figure S1, the wavelength range is extended in order to show how both the symmetric and the antisymmetric mode are affected by the sample strain. In the case of the SRR-bar, the symmetric mode, which is largely due to the nanowire resonance, is almost completely unaffected by changing the coupling distance with the other resonator. This was discussed in greater detail in previous work 1 .

Engineering metamaterials with tunable resonances from mid-infrared to near-infrared wavelengths could have far-reaching consequences for chip based optical devices, active filters, modulators, and sensors. Utilizing the metal-insulator phase transition in vanadium oxide (VO(2)), we demonstrate frequency-tunable metamaterials in the near-IR range, from 1.5 - 5 microns. Arrays of Ag split ring resonators (SRRs) are patterned with e-beam lithography onto planar VO(2) and etched via reactive ion etching to yield Ag/VO(2) hybrid SRRs. FTIR reflection data and FDTD simulation results show the resonant peak position red shifts upon heating above the phase transition temperature. We also show that, by including coupling elements in the design of these hybrid Ag/VO(2) bi-layer structures, we can achieve resonant peak position tuning of up to 110 nm.

Metamaterials can be designed to operate at frequencies from the visible to the mid-IR, making these structures useful for both refractive index sensing and surface-enhanced infrared absorption spectroscopy. Here we investigate how the mechanical deformation of compliant metamaterials can be used to create new types of tunable sensing surfaces. For split ring resonator based metamaterials on polydimethylsiloxane we demonstrate refractive index sensing with figures of merit of up to 10.1. Given the tunability of the resonance of these structures through the infrared after fabrication, they are well suited for detection of the absorption signal of many typical vibrational modes. The results highlight the promise of postfabrication tunable sensors and the potential for integration.

Abstract:We have integrated lithographically patterned VO 2 thin films grown by pulsed laser deposition with silicon-on-insulator photonic waveguides to demonstrate a compact in-line absorption modulator for use in photonic circuits. Using single-mode waveguides at λ = 1550 nm, we show optical modulation of the guided transverse-electric mode of more than 6.5 dB with 2 dB insertion loss over a 2-µm active device length. Loss is determined for devices fabricated on waveguide ring resonators by measuring the resonator spectral response, and a sharp decrease in resonator quality factor is observed above 70 °C, consistent with switching of VO 2 to its metallic phase. A computational study of device geometry is also presented, and we show that it is possible to more than double the modulation depth with modified device structures. . 12. T. Ido, S. Tanaka, M. Suzuki, M. Koizumi, H. Sano, and H. Inoue, "Ultra-high-speed multiple-quantum-well electro-absorption optical modulators with integrated waveguides," J. Lightwave Technol. 14(9), 2026-2034 (1996). 13. G. Gopalakrishnan, D. Ruzmetov, and S. Ramanathan, "On the triggering mechanism for the metal-insulator transition in thin film VO2 devices: electric field versus thermal effects," J. (7), 4621-4628 (1996). ©2010 Optical Society of America

Abstract:We demonstrate narrow transmission resonances at near-infrared wavelengths utilizing coupled asymmetric split-ring resonators (SRRs). By breaking the symmetry of the coupled SRR system, one can excite dark (subradiant) resonant modes that are not readily accessible to symmetric SRR structures. We also show that the quality factor of metamaterial resonant elements can be controlled by tailoring the degree of asymmetry. Changing the distance between asymmetric resonators changes the coupling strength and results in resonant frequency tuning due to resonance hybridization.