Abstract-Terahertz nonlinear superconducting metamaterials

Caihong Zhang¹, Biaobing Jin², Jiaguang Han^1,3, Iwao Kawayama¹, Hironaru Murakami¹, Jingbo Wu², Lin Kang², Jian Chen², Peiheng Wu², and Masayoshi Tonouchi¹

¹Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871, Japan
²Research Institute of Superconductor Electronics, Nanjing University, Nanjing 210093, China
³Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China 

http://apl.aip.org/resource/1/applab/v102/i8/p081121_s1?isAuthorized=no&view=print 

We investigate the nonlinear effect of a planar superconducting metamaterial made from niobium nitride (NbN) at terahertz frequencies. As the variation of the incident intense terahertz field alters the intrinsic conductivity in the NbN, a consequent giant amplitude modulation is observed due to the strong nonlinearities. The high sensitivity of the chosen metamaterial even allows observing the nonlinear behaviors at various temperatures, but the resonance modulation induced by the nonlinear effect was distinct from that induced by the heating effect. The presented results illustrate a clever implementation of strongly enhanced nonlinearities and thus may bring nonlinear metamaterials into novel applications