Experimental demonstration of negative refraction and subwavelength imaging by left-handed composite metamaterials
Author
Özbay, Ekmel
Aydın, Koray
Özkan, Gonca
Bulu, İrfan
Date
2006Source Title
Materials Research Society Symposium Proceedings, Symposium J – Negative Index Materials – From Microwave to Optical
Print ISSN
0272-9172
Publisher
Cambridge University Press
Volume
919
Pages
43 - 54
Language
English
Type
Conference PaperItem Usage Stats
140
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Abstract
We report a true left-handed (LH) behavior and focusing in a composite metamaterial consisting of periodically arranged split ring resonator (SRR) and wire structures. The magnetic resonance of the SRR structure is demonstrated by comparing the transmission spectra of SRRs with that of closed SRRs. We confirmed experimentally that the effective plasma frequency of the LH material composed of SRRs and wires is lower than the plasma frequency of the wires. A well-defined left-handed transmission band with a peak value of -1.2 dB (-0.3 dB/cm) is obtained. We also report the transmission characteristics of a 2D composite metamaterial (CMM) structure in free space. At the frequencies where left-handed transmission takes place, we experimentally confirmed that the CMM structure has effective negative refractive index. Phase shift between consecutive numbers of layers of CMM is measured and phase velocity is shown to be negative at the relevant frequency range. Refractive index values obtained from the refraction experiments and the phase measurements are in good agreement and the experimental results agree extremely well with the theoretical calculations. By measuring the refracted electromagnetic (EM) waves from a LHM slab, we found an effective refractive index of -1.86. A 2D scanning transmission measurement technique was used to measure the intensity distribution of the electromagnetic (EM) waves that radiate from the point source. The flat lens behavior of a 2D CMM slab was demonstrated for two different point source distances of ds = 0.5λ and λ. The full width at half maximum of the focused beams is 0.36λ and 0.4λ, respectively, which are both below the diffraction limit. © 2006 Materials Research Society.
Keywords
Composite materialsElectromagnetic wave diffraction
Light transmission
Phase velocity
Resonators
Composite metamaterial (CMM)
Metamaterials
Negative refraction
Plasma frequency
Split ring resonator (SRR)
Refractive index