We will discuss studies of nanoantennas for coupling light into bright, sub-diffraction-limited near-field spots. The antennas have much longer cutoff wavelengths than regularly-shaped aperture antennas, and are designed to strongly resonant. The gain of the antenna is further increased with additional surface features, or by arranging antenna arrays so that the antenna apertures are strongly coupled via magnetic field and are resonantly excited. Numerical and experimental studies have shown that these antennas can provide optical transmission as much as six orders of magnitude higher than an aperture with a comparable size. In many cases, the fundamental mechanisms for field enhancement are found to be the waveguide resonant effect (in single aperture and aperture array) and the plasmonic resonant effect, or the combination of the two. We demonstrate that these high-gain antenna apertures can be used in a wide range of engineering applications. We developed an antenna array-based parallel nanolithography system and a nanomaterials growth CVD system. Silicon nanowire arrays are grown in parallel, at precise locations on a substrate. This work is supported by the National Science Foundation and the Defense Advanced Research Project Agency.
Xianfan Xu is a Professor of Mechanical Engineering at Purdue University. He obtained his M.S. (1991) and Ph.D. (1994) degrees in Mechanical Engineering from the University of California, Berkeley. His current research is on laser based micro- and nano-engineering, including nanoscale laser machining/lithography, development of optical MEMS and NEMS, and near field nano-optics.
MGRN 121, Purdue University, West Lafayette, IN