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Sponsored by the Office of Naval Research, the National Science Foundation Nanoscale Interdisciplinary Research Team (NIRT) program, the Defense Advanced Research Project Agencies (DARPS) and the Purdue Center for Advanced Manufacturing We investigate techniques for concentrate light into a nanoscale domain, i.e., much smaller than the diffraction limit. Optical antenna based on ridged waveguide concept is developed for this purpose. These nanometer size, high intensity light spots are used as light sources for nano-lithography applications. Arrays of antennas are used for parallel manufacturing, thus, increasing the throughput of the manufacturing process. We also conduct the fundamental research, including nano-optics, high precision control, and nanoscale energy transfer. We have developed numerical methods for optimizing nanoscale antennas and have developed our own near field scanning optical microscopes (NSOM) for characterizing field distributions of the antennas. Theory: Ridge nanoapertures provides unique properties of nanoscale optical near-field confinement combined with high optical transmission, that is enabled by the confined waveguide propagation mode, resonant optical transmission and excitation of localized surface plasmon.
Design: finite-deference time-domain (FDTD) numerical computations are performed to optimize the dimensions of ridge nanoapertures with desired optical properties: nanoscale optical near field and enhanced optical transmission.
Characterization: near-field scanning optical microscopes (NSOM) with sub-50 nm optical resolution has developed to characterize the optical near field from the ridge nanoapertures.
Nanolithography: A novel lithography method using high transmission ridge apertures has been developed. Experimental results show enhanced transmission and light concentration properties of C, H and bow-tie apertures compared to square and rectangular apertures of the same opening area.
Near field scanning optical microscope Nanolithography system
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