Micromachined tunable metamaterials for terahertz application

This doctorate thesis focuses on the design, fabrication and experiment of reconfigurable metamaterials for THz wave modulation using micromachined fabrication process. Specifically, the optical response of the metamaterial are tuned in three aspects, i.e. the magnetic response, the electric response and the optical activity. The first part reports a magnetic response control through a reconfigurable material. The magnetic coupling strength is changed in real time by metamolecule reconfiguration, which is realized through micromachined technology. The second part focuses on the electric response tunable metamaterial in THz spectrum. The electric resonance is manipulated by tailoring different coupling effects, including the electromagnetic induced transparency (EIT)-like effect and the conductive coupling effect. Correspondingly, the control of a narrow transmitted band and the switching on a strong electric resonance are realized. The third part works on the metamaterial for tunable optical activity in THz regime. Two different metamaterials are proposed for the optical activity realization. In the planar metamaterial, significant polarization rotation is demonstrated and is reversed by tuning the chiral structure to its enantiomer shape. While in the semi-3D structure, intrinsic chirality is realized through a single layered stereo structure. Strong optical activity is derived and changed for different structure sizes. In conclusions, tunabilities on the magnetic resonance, the electric resonance and the optical activity in THz wave are realized through the metamaterial reconfiguration, which have high potential applications in optical filter, switch and polarization rotator, etc.DOCTOR OF PHILOSOPHY (EEE