Date: Monday, January 9, 2012. 4:15 PM.
Location: Nano 232 (Center for Nanoscale Science and Engineering)
January 9, 20124:15 PM, Nano Bldng 232 (Refreshments 4 PM)http://campus-map.stanford.edu/index.cfm?ID=04-040 - Map Nano-Optics of Plasmonic Optical Tweezers, SERS Substrates, and Multi-Colored Silicon Nanowires Kenneth B. CrozierSchool of Engineering and Applied SciencesHarvard University Field enhancement from surface plasmon structures presents new opportunities for optical manipulation and surface enhanced Raman spectroscopy (SERS). We demonstrate three configurations for manipulating nanoparticles using the optical forces from surface plasmons. In the first, we propel nanoparticles using surface plasmon polaritons (SPPs) on a thin gold film (NanoLett 2009). In the second, we trap microparticles with counter-propagating SPPs on a gold stripe (NanoLett 2010). In the third, we demonstrate a gold nanopillar plasmonic tweezer (Nature Communications 2011). The substrate acts as a heat sink, and simulations predict a ~100-fold reduction in heating compared to previous designs. We describe our work on metal nanoparticle substrates for SERS. We demonstrate that periodic metal nanoparticle arrays can exhibit spectrally narrow surface plasmon resonances, with numerical simulations predicting considerably enhanced optical near‐fields (APL 2008). We describe a novel SERS substrate with double plasmon resonances, which enables field enhancement at both pump and Stokes frequencies (ACS Nano 2010). We describe a method by which we lithographically fabricate pairs of nanoparticles with gaps as small as 3 nm, producing SERS enhancements almost two orders of magnitude larger than those with 18 nm gaps (Small 2011). Lastly, we demonstrate that vertical silicon nanowires take on a surprising variety of (diameter-dependent) colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, and arises from the guided mode properties of the individual nanowires (NanoLett 2011). Biography Ken Crozier is an Associate Professor of Electrical Engineering at Harvard University. His research interests are in nano-optics, including plasmonics for surface enhanced Raman spectroscopy and optical forces, optofluidics, and semiconducting nanowires. He received his undergraduate degrees in Electrical Engineering and Physics at the University of Melbourne, Australia. He was awarded the L.R. East Medal (university medal in engineering) by the University of Melbourne. He received his PhD in Electrical Engineering from Stanford University in 2003. In 2008, he was a recipient of an NSF CAREER award and a Loeb Chair at Harvard, an endowed, four-year position for untenured faculty. --------------------------------------------------------------------------The Optics and Electronics Seminar Series is sponsored by the Department of Applied Physics, andGinzton Laboratory-------------------------------------------------------------------------- Upcoming Talks (Joe Kahn, Organizer): Jan 23, 2012Hatice Altug, Dept. of Electrical and Computer Engineering, Boston University Jan 30, 2012 John Bowers, Dept. of Electrical and Computer Engineering, UC Santa Barbara "Ultralow Loss Waveguide Technology, Devices and Opportunities"
Location: Nano 232 (Center for Nanoscale Science and Engineering)
January 9, 20124:15 PM, Nano Bldng 232 (Refreshments 4 PM)http://campus-map.stanford.edu/index.cfm?ID=04-040 - Map Nano-Optics of Plasmonic Optical Tweezers, SERS Substrates, and Multi-Colored Silicon Nanowires Kenneth B. CrozierSchool of Engineering and Applied SciencesHarvard University Field enhancement from surface plasmon structures presents new opportunities for optical manipulation and surface enhanced Raman spectroscopy (SERS). We demonstrate three configurations for manipulating nanoparticles using the optical forces from surface plasmons. In the first, we propel nanoparticles using surface plasmon polaritons (SPPs) on a thin gold film (NanoLett 2009). In the second, we trap microparticles with counter-propagating SPPs on a gold stripe (NanoLett 2010). In the third, we demonstrate a gold nanopillar plasmonic tweezer (Nature Communications 2011). The substrate acts as a heat sink, and simulations predict a ~100-fold reduction in heating compared to previous designs. We describe our work on metal nanoparticle substrates for SERS. We demonstrate that periodic metal nanoparticle arrays can exhibit spectrally narrow surface plasmon resonances, with numerical simulations predicting considerably enhanced optical near‐fields (APL 2008). We describe a novel SERS substrate with double plasmon resonances, which enables field enhancement at both pump and Stokes frequencies (ACS Nano 2010). We describe a method by which we lithographically fabricate pairs of nanoparticles with gaps as small as 3 nm, producing SERS enhancements almost two orders of magnitude larger than those with 18 nm gaps (Small 2011). Lastly, we demonstrate that vertical silicon nanowires take on a surprising variety of (diameter-dependent) colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, and arises from the guided mode properties of the individual nanowires (NanoLett 2011). Biography Ken Crozier is an Associate Professor of Electrical Engineering at Harvard University. His research interests are in nano-optics, including plasmonics for surface enhanced Raman spectroscopy and optical forces, optofluidics, and semiconducting nanowires. He received his undergraduate degrees in Electrical Engineering and Physics at the University of Melbourne, Australia. He was awarded the L.R. East Medal (university medal in engineering) by the University of Melbourne. He received his PhD in Electrical Engineering from Stanford University in 2003. In 2008, he was a recipient of an NSF CAREER award and a Loeb Chair at Harvard, an endowed, four-year position for untenured faculty. --------------------------------------------------------------------------The Optics and Electronics Seminar Series is sponsored by the Department of Applied Physics, andGinzton Laboratory-------------------------------------------------------------------------- Upcoming Talks (Joe Kahn, Organizer): Jan 23, 2012Hatice Altug, Dept. of Electrical and Computer Engineering, Boston University Jan 30, 2012 John Bowers, Dept. of Electrical and Computer Engineering, UC Santa Barbara "Ultralow Loss Waveguide Technology, Devices and Opportunities"