Abstract-Free-standing terahertz chiral meta-foils exhibiting strong optical activity and negative refractive index

Jianfeng Wu¹, Binghao Ng², Shuvan P. Turaga¹, Mark B. H. Breese^1,3, Stefan A. Maier², Minghui Hong⁴, Andrew A. Bettiol¹, and Herbert O. Moser^5
1Department of Physics, Center for Ion Beam Applications (CIBA), National University of Singapore, 2 Science Drive, Singapore 
²Department of Physics, Imperial College, London SW7 2AZ, United Kingdom 
³Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, 117603 Singapore 
⁴Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576 Singapore 
⁵Karlsruhe Institute of Technology (KIT), Network of Excellent Retired Scientists (NES), and Institute of Microstructure Technology (IMT), Postfach 3640, 76021 Karlsruhe, Germany 

http://apl.aip.org/resource/1/applab/v103/i14/p141106_s1?isAuthorized=no

A chiral meta-foil consisting of a self-supported square array of interconnected conjugated rosettes is demonstrated at terahertz frequencies. It exhibits strong optical activity and circular dichroism. Negative refractive index with a figure-of-merit as high as 4.2 is achieved, attributed to its free-standing nature. Experimental results are in good agreement with numerical simulation. Free-standing chiral meta-foils provide a unique approach to create a completely all-metal chiral metamaterial, which can be flexibly integrated into optical setups while eliminating dielectric insertion losses.

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