Demonstration of metal-dielectric negative-index metamaterials with improved performance at optical frequencies

We experimentally demonstrate a comparatively low-loss negative-index metamaterial with the magnitude of the real part of the index comparable with the imaginary part. Over 40% transmission is achieved in the negative-index region by structural adjustment of the impedance matching between the metamaterial and the air-substrate claddings. This structure has the potential of achieving high transmission and small loss in the negative-index region. (c) 2006 Optical Society of America.