(Optical Society of America, 2008) Beruete Díaz, Miguel; Navarro Cía, Miguel; Sorolla Ayza, Mario; Campillo, Igor; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
This work presents the design of a planoconcave parabolic
negative index metamaterial lens operating at millimeter wavelengths
fabricated by using stacked subwavelength hole arrays. A staircase
approximation to the ideal parabola profile has been done by removing step
by step one lattice in each dimension of the transversal section. Theory
predicts power concentration at the focal point of the parabola when the
refractive index equals -1. Both simulation and measurement results exhibit
an excellent agreement and an asymmetrical focus has been observed. The
possibility to design similar planoconcave devices in the terahertz and
optical wavelengths could be a reality in the near future.
(Optical Society of America, 2008) Navarro Cía, Miguel; Beruete Díaz, Miguel; Sorolla Ayza, Mario; Campillo, Igor; Ingeniería Eléctrica y Electrónica; Ingeniaritza Elektrikoa eta Elektronikoa
Metamaterial structures are artificial materials that show
unconventional electromagnetic properties such as negative refraction
index, perfect lenses, and invisibility. However, losses are one of the big
challenges to be surpassed in order to design practical devices at optical
wavelengths. Here we report negative refraction in a prism engineered by
stacked sub-wavelength hole arrays. These structures exhibit inherently an
extraordinary optical transmission which could offer a solution to the
problem of losses at optical wavelengths. It is shown the possibility to
obtain negative indices of refraction starting from near to zero values. Our
work demonstrates by a direct experiment the feasibility of engineering
negative refraction by just drilling sub-wavelength holes in metallic plates
and stacking them.
