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Nanophotonics with subwavelength apertures: theories and applications.

This dissertation presents subwavelength optics with focus on the theory and applications
of subwavelength apertures in a metal film. Two main issues regarding the
optics with subwavelength apertures are investigated. As the first issue, the extraordinary
optical transmission (EOT) through a single hole in a metallic waveguide is
presented. A total transmission through a single subwavelength aperture is theoretically
predicted for a perfect electric conductor regardless of the aperture size, without
relying on aperture arrays and surface corrugations as presented in previous works.
The waveguide EOT is then applied to boost the optical throughput of an apertured
near-field scanning optical microscope (NSOM) probe. Using a new structure for
the apertured NSOM probe which allows for waveguide EOT, the optical throughput
and the damage threshold are boosted by 100× and 40× as compared to a conventional
structure, and the experimental findings are backed-up by comprehensive
finite-difference time-domain (FDTD) simulations. Single fluorescent molecules are
scanned using the EOT apertured NSOM probe, and a spatial resolution of 62 nm is
achieved. As the second issue, subwavelength apertures are found useful for optical trapping.
A small dielectric particle can significantly change the optical transmission through
an aperture by dielectric loading, and subsequently, a large optical force is induced which favors trapping. A self-induced back-action (SIBA) optical trap is designed
using a circular nanohole in a gold film. Trapping of 50 nm polystyrene particle
is experimentally achieved, which is not possible using a conventional single beam
optical tweezers. The circular nanohole SIBA trap works beyond the perturbative
regime, as proven by FDTD simulations and a Maxwell stress tensor analysis. We
further improve the nanohole trapping using a double-nanohole, which is more sensitive
for small dielectric changes due to the intense local field enhancement between
its two sharp tips. A single 12 nm silica sphere is experimentally trapped using the
double-nanohole, as the smallest trapped dielectric particle reported. We also achieve
the trapping of a single protein – a bovine serum albumin (BSA) protein with a hydrodynamic
radius of 3.4 nm in the folded form. The trapped BSA is also unfolded
by the large optical force, as confirmed by experiments with changing optical power
and changing pH. The high signal-to-noise ratio of 33 in monitoring single protein
trapping and unfolding shows a tremendous potential for using the double-nanohole
as a sensor for protein binding events at a single molecule level. / Graduate

  1. http://hdl.handle.net/1828/3986
  2. A. Ahmed, Y. Pang, G. Hajisalem, and R.Gordon, "Antenna Design for Directivity Enhanced Raman Spectroscopy," International Journal of Optics 2012, 729138, (2012).
  3. Y. Pang, and R. Gordon, "Optical Trapping of a Single Protein," Nano Letters, 12(1), 402–406, (2012).
  4. Y. Pang, and R. Gordon, "Optical Trapping of 12 nm Dielectric Spheres Using Double-Nanoholes in a Gold Film," Nano Letters 11(9), 3763¨C3767, (2011).
  5. A. Weber-Bargioni, A. Schwartzberg, M. Cornaglia, A. Ismach, J. J. Urban, Y. Pang, R. Gordon, J. Bokor, M. B. Salmeron, D. F. Ogletree, P. Ashby, S. Cabrini, and P. J. Schuck, "Hyperspectral Nanoscale Imaging on Dielectric Substrates with Coaxial Optical Antenna Scan Probes," Nano Letters 11(3), 1201-1207, (2011).
  6. Q. Min, Y. Pang, D. J. Collins, N. A. Kuklev, K. Gottselig, D. W. Steuerman, and R. Gordon, "Substrate-based platform for boosting the surface-enhanced Raman of plasmonic nanoparticles," Optics Express 19(2), 1648-1655 (2011).
  7. L. Neumann., Y. Pang, A. Houyou., M. L. Juan., R. Gordon, and N. F. van Hulst, "Extraordinary Optical Transmission Brightens Near-Field Fiber Probe," Nano Letters 11(2), 355-360 (2011).
  8. M. L. Juan, R.Gordon, Y. Pang, F. Eftekhari, and R. Quidant, "Self-Induced Back-Action Optical Trapping of Dielectric Nanoparticles," Nature Physics 5, 915-919 (2009).
  9. Y. Pang, A. N. Hone, P. P. M. So, and R. Gordon, "Total Optical Transmission Through a Small Hole in a Metal Waveguide Screen," Optics Express 17(6), 4433-4441, (2009).
  10. Y. Pang, and R. Gordon, "Metal Nano-Grid Reflective Wave Plate," Optics Express 17(4), 2871-2879, (2009).
Identiferoai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/3986
Date08 May 2012
CreatorsPang, Yuanjie
ContributorsGordon, Reuven
Source SetsUniversity of Victoria
LanguageEnglish, English
Detected LanguageEnglish
TypeThesis
RightsAvailable to the World Wide Web

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