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SUMMARY:Nano-Optics of Plasmonic Optical Tweezers\, SERS Substrates\, and 
 Multi-Colored Silicon Nanowires
DTSTART:20120907T110000
DTSTAMP:20260924T195657Z
UID:9bf6df13a98fd5bbe7975085db3870b50a323d77b58a78c3f6fa52fa
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Ken Crozier\, Harvard University\nField enhancement from
  surface plasmon structures presents new opportunities for optical manipul
 ation and surface enhanced Raman spectroscopy (SERS). We demonstrate three
  configurations for manipulating nanoparticles using the optical forces fr
 om surface plasmons. In the first\, we propel nanoparticles using surface 
 plasmon polaritons (SPPs) on a thin gold film (NanoLett 2009). In the seco
 nd\, we trap microparticles with counter-propagating SPPs on a gold stripe
  (NanoLett 2010). In the third\, we demonstrate a gold nanopillar plasmoni
 c tweezer (Nature Communications 2011). The substrate acts as a heat sink\
 , and simulations predict a ~100-fold reduction in heating compared to pre
 vious designs. We describe our work on metal nanoparticle substrates for S
 ERS. We demonstrate that periodic metal nanoparticle arrays can exhibit sp
 ectrally narrow surface plasmon resonances\, with numerical simulations pr
 edicting considerably enhanced optical near-fields (APL 2008). We describe
  a novel SERS substrate with double plasmon resonances\, which enables fie
 ld enhancement at both pump and Stokes frequencies (ACS Nano 2010). We des
 cribe a method by which we lithographically fabricate pairs of nanoparticl
 es with gaps as small as 3 nm\, producing SERS enhancements almost two ord
 ers of magnitude larger than those with 18 nm gaps (Small 2011). Lastly\, 
 we demonstrate that vertical silicon nanowires take on a surprising variet
 y of (diameter-dependent) colors covering the entire visible spectrum\, in
  marked contrast to the  gray color of bulk silicon. This effect is readi
 ly observable by bright-field microscopy\, and arises from the guided mode
  properties of the individual nanowires (NanoLett 2011).
LOCATION:SV 1717 https://plan.epfl.ch/?room==SV%201717
STATUS:CONFIRMED
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