Extraordinary optical transmission with negative index of refraction C. García-Meca, R. Ortuño, F.J. Rodríguez-Fortuño, A. Martínez, J. Martí Nanophotonics Technology Center, Universidad Politécnica de Valencia C.P. 46022, Camino de Vera, s/n, Valencia, Spain Fax: + 34 963877827; email: cargarm2@ntc.upv.es Abstract We present a metamaterial exhibiting extraordinary optical transmission and negative index of refraction in the same spectral band. The structure consists of a periodic metal film alternately perforated by slits and cy- lindrical holes displaying its properties at wavelengths around 600 nm (500 THz). 1. Introduction Nowadays, periodic sub-wavelength particle and hole arrays constitute a wide research field within nanophotonics [1]. Two of the most sought after phenomena based on these structures are extraordi- nary optical transmission (EOT) and negative refraction. The former lies on the coupling from incident light to surface plasmons in a drilled metallic sheet, where light undergoes an enhanced transmission, higher than that predicted for a single hole in a perfect conductor [2]. The second effect, negative re- fraction, is directly related to metamaterials, which gain their properties from their shape rather than from their composition and provide a way to attain negative refractive index media (NIM) [3]. In this work, we manage to combine the two effects in the same frequency range. From now on, we will refer to this phenomenon as NEOT (Negative refractive index Extraordinary Optical Transmission). 2. NIM-EOT metamaterial Consider a simple array of cylindrical holes as starting point (Fig. 1a), with periodicities a x =500nm, a y =330nm and a hole radius r = 110nm. The thickness of the film is t = 130 nm. Fig. 1b shows the corre- sponding normalized transmission T n defined as: hole ucell in out n A A P P T = (1) Fig. 1: a) Cylindrical hole array b) Normalized transmission spectrum x y z E k H 0 100 200 300 400 500 600 700 800 5 4 3 2 1 0 T n f (THz) a) b) 515