NEMS-Based Infrared Metamaterial via Tuning Nanocantilevers Within Complementary Split Ring Resonators

Dynamic control of the electromagnetic properties of metamaterials requires wide modulation bandwidth. Tunable metamaterials with large tunability and fast speed are thus highly desirable. Due to the small dimensions, subwavelength meta-atoms or resonant elements that constitute a metamaterial in the mid-to-near-infrared (IR) wavelength range are often not easy to be tuned at a high rate of several tens of megahertz (MHz). Here, we report on a nanoelectromechanical systems (NEMS)based tunable IR metamaterial realized by unique embedding of nanocantilevers into complementary split ring resonators (c-SRRs) suspended over individual wells. The optical field confined in the air gap of the c-SRR is strongly influenced by electrostatically induced mechanical deflection of the nanocantilever, thus modulating the reflection spectrum of the metamaterial. With the easy-to-implement tunable meta-atom design, the IR metamaterial with 800-nm-long cantilevers provides an ultrahigh mechanical modulation frequency of 32.26 MHz for optical signal modulation at a wavelength of 2.1 μm, and is rather easy to manufacture and operate. We envision a compact, efficient, and high-speed electrooptic modulation platform in the IR region using this NEMS tunable metamaterial technology.