Abstract
Large-area split ring resonators (SRRs) array is fabricated by laser micro-lens array (MLA) lithography on flexible Polyethylene Naphthalate (PEN) substrates. Multi-layer metamaterials are formed by stacking and bonding several layers of the laser fabricated metamaterials together. The resonance of the multi-layer metamaterials is enhanced significantly as compared to the single-layer metamaterials. The roll-off value of the half-wavelength resonant dip, which reflects the strength of resonance, increases significantly from 4.9 to 11.2 as the layer number increases from 1 to 5. A logarithm relationship between the amplitude of the resonant dip and the layer number is also studied, which indicates a flexible method to tune the strength of resonance by changing the layer number. The multi-layer metamaterials with the enhanced resonance can be used to make narrow band terahertz filters. (C) 2011 Optical Society of America