Delay and advance of Gaussian pulses propagated in superconducting metamaterial waveguide composed of split-ring resonators

YuHan Chang^1*, Vanna Chrismas Silalahi¹, Raul A. Robles Robles², Cen-Shawn Wu³, Ray-Kuang Lee², Watson Kuo¹

¹Department of Physics, National Chung Hsing University, Taichung, Taiwan
²Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan
³Department of Physics, National Chang-Hua University of Education, ChangHua, Taiwan

* Presenter:YuHan Chang, email:bread30724@gmail.com

The microwave transmission in one-dimensional(1D) resonator array composed of split-ring resonators(SRR) and complementary split-ring resonators is experimentally studied. The band structure of the 1D system can be engineered by arranging the configuration of ring orientation. For our experiment, arrays of 20 superconducting SRRs made of aluminum were made on a sapphire substrate. The collective modes at frequencies around 6 GHz show a high-quality factor of about 5000 at 20mK. The spectra show clearly a sharp π phase jump in transmission, which causes slow light effect, and show large phase inverse in reflection, which allows superluminal effect. The propagation of a Gaussian-shaped temporal pulse on resonance with the collective modes exhibits pronounced delay, of about 380 ns at 5.9836 GHz in transmission. On the contrary, the propagation of pulse shows pronounced advance, of about 230 ns at 6.023 GHz in reflection. The propagation of truncated Gaussian pulses more clearly illustrate the delay and advanced phenomena.

Keywords: split-ring resonators, slow light, superluminal effect, superconducting waveguide, metamaterial