Characterization of the tunable response of highly strained compliant optical metamaterials

Abstract

Metamaterial designs are typically limited to a narrow operating bandwidth that is predetermined by the fabricated dimensions. Various approaches have previously been used to introduce post-fabrication tunability and thus enable active metamaterials. In this work, we exploit the mechanical deformability of a highly compliant polymeric substrate to achieve dynamic, tunable resonant frequency shifts greater than a resonant linewidth. We investigate the effect of metamaterial shape on the plastic deformation limit of resonators. We find that, for designs in which the local strain is evenly distributed, the response is elastic under larger global tensile strains. The plastic and elastic limits of resonator deformation are explored and the results indicate that, once deformed, the resonators operate within a new envelope of elastic response. We also demonstrate the use of coupled resonator systems to add an additional degree of freedom to the frequency tunability and show that compliant substrates can be used as a tool to test coupling strength. Finally, we illustrate how compliant metamaterials could be used as infrared sensors, and show enhancement of an infrared vibration absorption feature by a factor of 225.