Ph.D. Thesis Defense - Joe Matteo

Joseph Anthony Matteo matteoja at stanford.edu
Tue May 10 11:11:32 PDT 2005


Hello Everyone,

 I'll be defending next Tuesday, May 17th, at 1:30pm in the Clark Center
Auditorium in Bio-X.  There will be refreshments at 1:15.  Hope you can
make it, and come see what I've been up to for the last (ahem!) years.

-----------------------------------------------------
Stanford University Ph.D. Oral Examination

¡§Design, Characterization and Application of Resonant Nano-Aperture
Near-Field Probes¡¨

Joseph A. Matteo, Dept. of Applied Physics
Clark Center Auditorium (Bio-X)
Tuesday, May 17, 2005
1:30p.m. ¡V 2:30p.m.
(Refreshments at 1:15)

In recent years, there has been an ongoing trend to investigate smaller,
more basic physical systems, create smaller devices, and encode information
more densely.  As these physical systems and their associated length scales
approach that of the wavelength of light, the diffraction limit becomes a
major impediment to achieving these goals optically.  One method for
overcoming this limit is to make these measurements in the near-field of a
sub-wavelength aperture.  Unfortunately, it has been shown that the power
throughput of apertures much smaller than a wavelength falls off as
(d/Ć)4.  I will present efforts to design, classify, and fabricate
resonantly shaped apertures shown to exhibit >1000 times throughput
enhancement in simulation and microwave experiments, for use in the optical
regime.  Such a high throughput nano-aperture would be an enormous asset for
use in single-molecule studies, data storage, optical lithography, and
nano-scale optical manipulation.  Any effective implementation of this
approach, however,  requires a systematic method for design,
characterization , and quantification of aperture performance.  Operating
at optical frequencies  presents many challenges as well.  In particular,
optical properties of metals, topological artifacts introduced by FIB
fabrication, and the strong coupling with measurement probes must be
understood and accounted for in order to properly design apertures and
interpret results.
 Individual transmission spectra taken using confocal spectroscopy showed
that the C-shaped apertures we designed exhibited from 13-22 times
enhancement over square apertures of the same area, which implies a 106
improvement over a square aperture modeled to produce the same near field
spot size. Furthermore, the location of this resonance was tuned over 70nm
simply by scaling the aperture dimensions.  Photon Scanning Tunneling
Microscopy (PSTM) was used to characterize the near-field performance of
C-apertures determined to be resonant at 633nm by the spectral study.   A
deeply sub-wavelength spot size was verified for these structures.
Detailed calibration studies were carried out to deconvolve the images with
the preferential collection efficiency of the probe for certain field
components, and its finite collection range.  A general formalism was
developed for extraction of quantitative information from near-field
images.  Advanced numerical studies were carried out on novel fractal
configurations of nano-apertures which were shown to elicit throughput
enhancements yet another order of magnitude larger and several times
enhancement in achievable resolution.  Applications of these designs will
also be presented from a wide range of areas including near-field data
storage and lithography, nano-scale optical trapping, and enhanced
near-field optical probe manufacturing.
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