We investigate the effect of metal permittivity on resonant transmission of metamaterials by terahertz time-domain spectroscopy. Our experimental results on double split-ring resonators made from different metals confirm the recent numerical simulations [ Phys. Rev. E 65, 036622 (2002) ] that metamaterials exhibit permittivity-dependent resonant properties. In the terahertz regime, the measured inductive–capacitive resonance is found to strengthen with a higher ratio of the real to the imaginary parts of metal permittivity, and this remains consistent at various metal thicknesses. Furthermore, we found that metamaterials made even from a generally poor metal become highly resonant owing to a drastic increase in the value of the permittivity at terahertz frequencies.
© 2008 Optical Society of America
Original Manuscript: February 15, 2008
Manuscript Accepted: May 12, 2008
Published: June 27, 2008
Ranjan Singh, Abul K. Azad, John F. O'Hara, Antoinette J. Taylor, and Weili Zhang, "Effect of metal permittivity on resonant properties of terahertz metamaterials," Opt. Lett. 33, 1506-1508 (2008)