Monday, 1 August 2011

Tunable resonance enhancement of multi-layer terahertz metamaterials fabricated by parallel laser micro-lens array lithography on flexible substrates

Z. C. Chen, N. R. Han, Z. Y. Pan, Y. D. Gong, T. C. Chong, and M. H. Hong



Optical Materials Express, Vol. 1, Issue 2, pp. 151-157 (2011)       doi:10.1364/OME.1.000151


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.


“The samples are characterized by a Terahertz Time Domain Spectroscopy (THz-TDS,
TPS3000, Teraview Inc.) in transmission mode at a normal incidence. The electric field of the
incident terahertz wave is aligned parallel to the gap-bearing side of the SRRs as illustrated in
Fig. 1 (B). All the transmission spectra of the samples with different layer numbers are
normalized against the reference transmission spectrum of Nitrogen gas environment [30]”