Large-area, infrared nanophotonic materials fabricated using interferometric lithography

Interferometric lithography IL is an ideal technique for the parallel fabrication of large-area periodic patterns at nanometer scales. Compared to other lithography techniques, IL has the optics advantage of parallel fabrication over large areas, resulting high efficiency and low cost. By combining IL with self-aligned semiconductor processing and epitaxial techniques, complicated nanoscale structures can be fabricated for various applications. Recently, the interaction between light and metal films has attracted much attention. In this paper, fabrication of two novel metal based structures which show unconventional optical properties and have great potential applications is discussed. Negative refractive index material NIM was first studied a long time ago. However, because of the absence of naturally occurring NIM, the full theoretical and experimental study of the implications of NIM was not carried out at the time. The recent demonstration of the first negative-index artificial structure in the microwave region has rekindled interest in this topic. Until now, most of the experimental work has been focused on the microwave region because of the comparative ease of fabrication, and it has been difficult to scaling the microwave structures down to optical frequencies. Recently, several works have extended a resonant negative permeability to the THz domain, however, the demonstration of a negative refractive index material at infrared wavelengths has only very recently occurred. In this paper, we describe the fabrication details of a thin metallic structure that shows a negative refractive index around 2 m. This is among the first demonstrations of a metal-based metamaterial with a negative refraction at near IR wavelengths. The demonstration of enhanced transmission through subwavelength metallic hole arrays has attracted a lot of attention. The basic mechanism for this phenomenon is generally ascribed to the coupling between the incoming light and surface plasmons, although other mechanisms have been proposed. Much higher transmission can be obtained by replacing the arrays of circular holes with coaxial arrays, as has been theoretically and experimentally demonstrated. By applying IL and self-alignment tech-