Silicon-immersed terahertz plasmonic structures

A Bull's eye (BE) plasmonic structure exhibits a powerful property of highly enhanced light transmission through a sub-wavelength aperture. However, the BE structure in the terahertz (THz) region exhibits the problems of a relatively low THz-field enhancement factor and a large area with an increasing groove number. Here, we report on a design of a THz BE structure that utilizes a solid immersion method based on the high refractive index of a silicon (Si) material. By fabricating a deep-etched Si template covered with a gold film, we achieved a greatly enhanced THz transmission with an enhancement factor of up to similar to 10(8) and also miniaturized the structure size by the factor of 11. These features demonstrate that the BE performance can be further improved by engineering dielectric materials. Published by AIP Publishing.