A Micromachined Reconfigurable Metamaterial via Reconfiguration of Asymmetric Split-Ring Resonators

A micromachined reconfigurable metamaterial is presented, whose unit cell consists of a pair of asymmetric split-ring resonators (ASRRs); one is fixed to the substrate while the other is patterned on a movable frame. The reconfigurable metamaterial and the supporting structures (e. g., microactuators, anchors, supporting frames, etc.) are fabricated on a silicon-on-insulator wafer using deep reactive-ion etching (DRIE). By adjusting the distance between the two ASRRs, the strength of dipole-dipole coupling can be tuned continuously using the micromachined actuators and this enables tailoring of the electromagnetic response. The reconfiguration of unit cells endows the micromachined reconfigurable metamaterials with unique merits such as electromagnetic response under normal incidence and wide tuning of resonant frequency (measured as 31% and 22% for transverse electric polarization and transverse magnetic polarization, respectively). The reconfiguration could also allow switching between the polarization-dependent and polarization-independent states. With these features, the micromachined reconfigurable metamaterials may find potential applications in transformation optics devices, sensors, intelligent detectors, tunable frequency-selective surfaces, and spectral filters.