Bulletin of the American Physical Society
78th Annual Meeting of the Southeastern Section of the APS
Volume 56, Number 9
Wednesday–Saturday, October 19–22, 2011; Roanoke, Virginia
Session NC: Nanoscale Optics |
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Chair: Richard Haglund, Vanderbilt University Room: Crystal Ballroom C |
Saturday, October 22, 2011 8:30AM - 9:00AM |
NC.00001: Nanoplasmonics and Metamaterials with Low Loss and Gain Invited Speaker: Nanoplasmonics and Metamaterials have become an important research topic because of their interesting physics and exciting potential applications, ranging from sensing and biomedicine to nanoscopic imaging and information technology. However, many applications are hindered by one common cause -- absorption loss in metal. We have shown the loss of surface plasmon can be conquered by modifying the surface structure of metal, and also can be compensated with optical gain. We also have observed the stimulated emission of surface plasmon, and demonstrated the spaser (nanolaser) supported by localized surface plasmon. We have studied the non-metallic metamaterials, which do not suffer from the damping loss of metals, including semiconductors and laser dyes. We have shown indium tin oxide (ITO) is more suitable for the nanoplasmonic applications in the infrared range than Au. We also have shown that high concentrated laser dyes exhibit negative real parts of the electric permittivity, and their dielectric functions can be controlled by laser illumination. With no doubts, such materials can revolutionize the entire technological fields of nanoplasmonics and metamaterials.\\[4pt] In collaboration with M. Noginov, Norfolk State University. [Preview Abstract] |
Saturday, October 22, 2011 9:00AM - 9:30AM |
NC.00002: Pattern Transfer Nanomanufacturing Invited Speaker: We report programmed fluidic assembly of $\sim $12 nm diameter Fe$_{3}$O$_{4}$ nanoparticles into hierarchically-patterned architectures using the confined magnetic fields that are emitted from transitions written onto magnetic disk drive media. When combined with a controlled external field, our approach yields both laterally-programmed assemblies of nanoparticles over cm length scales and vertically-programmed periodic topography. After assembly, the 3D arrays of nanoparticles are transferred to a flexible and transparent polymer film by spin-coating and peeling. We determine the total transferred magnetic moment as a function of nanoparticle concentration and exposure time, and explain the variation in moment for low concentrations using a simple hydrodynamic model. However, this model is insufficient to explain the transferred moment at higher concentrations, likely because of the combination of dynamically-changing fields during assembly, and field-shielding near the medium surface, both of which will play an enhanced role at higher nanoparticle concentrations. We will discuss potential applications of this technology for creating optoelectronic and biomedical devices. [Preview Abstract] |
Saturday, October 22, 2011 9:30AM - 10:00AM |
NC.00003: High Surface Area Vertically Aligned Metal Oxide Nanostructures for Dye-Sensitized Photoanodes by Pulsed Laser Deposition Invited Speaker: Dye Sensitized Solar Cells (DSSCs) differ from conventional semiconductor devices in that they separate the function of light absorption from charge carrier transport. At the heart of a DSSC is a metal oxide nanoparticle film, which provides a large effective surface area for adsorption of light harvesting molecules. The films need to be thick enough to absorb a significant fraction of the incident light but increased thickness results in diminished efficiencies due to augmented recombination. Here we introduce a new structural motif for the photoanode in which the traditional random nanoparticle oxide network is replaced by vertically aligned bundles of oxide nanocrystals. The direct pathways provided by the vertical structures appear to provide for enhanced collection efficiency for carriers generated throughout the device. The fabrication method is materials agnostic as similar structures will be shown in Nb2O5, TiO2 and SrTiO3. [Preview Abstract] |
Saturday, October 22, 2011 10:00AM - 10:30AM |
NC.00004: Enhanced nonlinear optics and other applications of resonant plasmonics Invited Speaker: A surface plasmon polariton is the result of a photon coupling to a collective charge excitation in an electron gas. It is the optical equivalent of ordinary electrical currents at lower frequencies. By this analogy, just as regular electronic circuits can have resonances at discrete frequencies, metal nanostructures can exhibit plasmonic resonances in the optical frequency regime. These resonances tend to concentrate the electromagnetic field intensity by several orders of magnitude within nanometer scale hotspots located at sharp corners or inside narrow gaps in the structure. This phenomenon can be used to enhance a number of different effects, such as Raman scattering, fluorescence efficiency and photochemical reactions. This talk will give an overview of some of our recent work in this area, focusing on using plasmons to enhance the second harmonic generation (SHG) from nonlinear optical films. In particular, we have shown that the addition of plasmonic nanoparticles to such a film can increase the SHG emission as much as 2000 times. We have applied this idea to SHG generation in tapered optical fiber, where we obtain quasi-phase matching by patterning the deposition of metal nanoparticles onto the otherwise uniform nonlinear film that coats the fiber. I will also discuss our recent work on plasmonically enhanced nonlinear microscopy and plasmon enhanced photovotaics. \\[4pt] In collaboration with Kai Chen, Chih-Yu Jao, Chalongrat Daengngam, Jeong-Ah Lee, and J. Randall Heflin, VirginiaTech, Department of Physics; Sungsool Wi, VirginiaTech, Department of Chemistry; Lauren Neely, Vladimir Kochergin, MicroXact, Inc.; and Yong Xu, Virginia Tech, Department of Electrical and Computer Engineering. [Preview Abstract] |
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