Photomodulation of Metamaterial: An Integrated Approach

摘要

In this paper, we present an integrated fabrication process for realizing a switching/modulation mechanism for negative index materials (NIMs) based on photoconductive coupling. The metamaterial element chosen is an array of regular copper split-ring resonator (SRR) that was fabricated on two different substrates: high-resistivity silicon (HRS) and fused silica glass. The switching mechanism proposed can be achieved through tuning the SRR gap and/or substrate conductivity. The photosensitive material of the SRR structure (amorphous silicon for the glass substrate samples and intrinsic silicon for the HRS substrate samples) upon illumination generates excess carriers that essentially shunt the gap capacitance thus diminishing the resonance response significantly. The response in terms of S-parameters is simulated using HFSS under varying magnitude of optical illumination. Our simulation with a single SRR to demonstrate total suppression of resonance amplitude with a high extinction ratio is applicable to NTMs comprising of both negative permeability and negative permittivity without any loss of generality. This method may provide a basis for long-sought practical applications and devices based on NTM in the fields of ultra-fast communications at RF and optical frequencies, sensing and imaging promising a potential of dramatically improving the performance of existing phased array antennas, optical beam-forming networks, antenna remoting and transportation of RF power through fiber-radio.