Metamaterial Enhanced Terahertz Spectroscopy of Biomolecules

As the field of metamaterials experiences exponential growth, an increasing number of studies have focused on understanding near-field coupling between arrays of metamaterials and their local environment. Examples include a second array of metamaterials, phonon bands in semiconductors, and even small molecules. In this work, we demonstrate metamaterial coupling to a thin film of biomolecules. Protein films are deposited onto arrays of gold split ring resonators (SRRs) on thin silicon nitride substrates. As the LC resonance of the SRR is tuned across the low frequency terahertz (THz) modes of the biomolecule, hybridization results in mode splitting. The thin substrates (400nm) and the large electric field enhancement intrinsic to the SRRs provide ultrasensitive detection of the THz modes in the protein, allowing for the THz response to be measured from thin films which would otherwise not be observable.