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Dive into the research topics where Yun Suk Jung is active.

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Featured researches published by Yun Suk Jung.


Applied Physics Letters | 2003

Role of surface plasmons in the optical interaction in metallic gratings with narrow slits

Zhijun Sun; Yun Suk Jung; Hong Koo Kim

We report an experimental study of the transmission of light through narrow slits in metallic gratings (Ag layer thickness of 100–400 nm, grating period of 370 or 780 nm, and slit width of 30–100 nm). Peak transmission of ∼60% is observed for TM polarization at a wavelength redshifted from the point of surface plasmon (SP) resonance at the metal/substrate interface. At the transmission minima, the angular dependence of reflection shows a sharp peak with minimum loss of optical power. Two types of surface plasmon excitation are found responsible for the observed transmission dips: (1) the SP resonance along the planes that comprise either the metal/air or metal/substrate interfaces and (2) the SP resonance localized along the surface that encloses each metal island separated by slits.


Journal of Physics B | 2007

Femtosecond microscopy of localized and propagating surface plasmons in silver gratings

Atsushi Kubo; Yun Suk Jung; Hong Koo Kim; Hrvoje Petek

Localized and propagating surface plasmons excited with 10 fs, 400 nm laser pulses in silver gratings are imaged with a sub-wavelength spatial resolution. Microscopic images of two-photon photoemission from the nanostructured silver surface representing nonlinear maps of surface plasmon fields are recorded with a photoemission electron microscope (PEEM). Tuning the laser wavelength into the resonance of a silver grating enhances the emission from the propagating mode and attenuates that from the localized modes. Time-resolved interferometric PEEM movies taken at 330 as/frame intervals reveal the dynamics of the oscillation and dephasing of individual localized surface plasmons.


Optics Express | 2009

Blue-shift of surface plasmon resonance in a metal nanoslit array structure

Yun Suk Jung; Jeff Wuenschell; Hong Koo Kim; Palwinder Kaur; David H. Waldeck

The adsorption of a self-assembled monolayer of molecules on a metal surface commonly causes a red-shift in its surface plasmon resonance. We report that the anomalous dispersion of surface plasmons in a Au nanoslit array structure can cause a blue-shift of optical transmission upon adsorption of a non-absorbing self-assembled monolayer of molecules. We develop a simple model that explains the blue-shift observed in the transmission spectra with monolayer adsorption in terms of the interplay of anomalous dispersion and the cavity resonance of surface plasmons in the nanoslit array.


Applied Physics Letters | 2006

High-sensitivity surface plasmon resonance spectroscopy based on a metal nanoslit array

Yun Suk Jung; Zhijun Sun; Jeff Wuenschell; Hong Koo Kim; Palwinder Kaur; Lei Wang; David H. Waldeck

We have chemically modified metal nanoslit array surfaces with alkanethiol self-assembled monolayers and have characterized the resulting spectral shift of optical transmission. Adsorption of a self-assembled monolayer (1.5nm thick) on a silver nanoslit array (slit width of 30–50nm and grating period of 360nm) is found to cause an 11nm redshift of the main transmission peak. Strong confinement of optical fields in the narrow slit region allows sensitive transduction of surface modification into a shift of surface plasmon resonance wavelength.


Applied Physics Letters | 2005

Dynamic evolution of surface plasmon resonances in metallic nanoslit arrays

Zhijun Sun; Yun Suk Jung; Hong Koo Kim

We have investigated surface plasmon interactions in a metallic nanoslit array structure that shows characteristic transmission spectra with well-defined transmission minima and maxima in the visible-to-infrared range. The time evolution of the surface plasmon resonances occurring in various different regimes of the spectra was analyzed by performing finite-difference time-domain analysis of the plasmon field, energy flow, and polarization charge distributions in the nanoslit array structure. At the transmission dip that corresponds to the surface plasmon resonance at metal/dielectric(substrate) interface, the polarization charges are found to distribute such that they form in-plane standing-wave oscillations along the dielectric side of the metal surface. At the transmission peak, surface plasmon waves oscillate along the periphery of each metal island with a quadrupolar distribution of polarization charges. At the longer wavelength regime, the polarization charges at each island show a dipolar distribut...


Applied Physics Letters | 2005

Blueshift of surface plasmon resonance spectra in anneal-treated silver nanoslit arrays

Yun Suk Jung; Zhijun Sun; Hong Koo Kim; J. R. Blachere

Silver nanoslit arrays were anneal treated in vacuum, and the effects on the surface morphology of silver and the surface plasmon resonance characteristics were investigated. Optical transmission through nanoslit arrays shows a distinctive change in the spectral profiles after annealing: A clear blueshift of the transmission peaks and dips (20nm shift for an anneal temperature of 150°C). Scanning electron microscopy reveals a morphological change of silver: Increased grain sizes, and smooth and round surface profiles after the anneal treatment. The observed blueshift of transmission spectra correlates well with the geometrical and dimensional changes of silver islands defined between slits, which are found to alter the surface plasmon resonance conditions involving various mechanisms in different regimes.


Applied Physics Letters | 2008

Near- to far-field imaging of free-space and surface-bound waves emanating from a metal nanoslit

Yun Suk Jung; Jeff Wuenschell; Tyler Schmidt; Hong Koo Kim

The authors report the radiation pattern (radial and angular distribution of light intensity) of a silver nanoslit measured in the near- to far-field regimes. In most far fields, the 1∕r dependence of intensity distribution, expected from a cylindrical wave emanating from a line source, is clearly observed. The glancing angle regime is found to be governed by the presence of surface plasmons, showing higher intensity closer to the metal surface. From the radiation patterns measured with a tilted-probe, radial-scan method, a branching ratio is quantitatively determined for the free-space radiation and surface plasmon components, emerging from the nanoslit.


Optics Express | 2010

Interaction of light with a metal wedge: the role of diffraction in shaping energy flow

Yonggang Xi; Yun Suk Jung; Hong Koo Kim

When a light wave hits a metal wedge structure, the metal surfaces respond to the incident light by generating both free-space and surface-bound waves. Here we present a physical model that elucidates electromagnetic interactions of an incoming planar wave with a simple semi-infinite 90 degrees metal wedge. We show that a metal wedge structure possesses an intrinsic capability of directing the incident power around the corner into the forward direction. Interplay of the boundary diffraction wave and the incident and reflection waves in the near field region of a metal corner is found to form a basis of the funneling phenomena that are commonly observed in metal nanoslit structures. Theory and experiment reveal that the incident wave propagating parallel to the sidewall destructively interferes with the boundary diffraction wave forming a depleted-energy-flow region along the glancing angle direction. A physical understanding of various electromagnetic phenomena associated with a metal wedge structure confirms rich potential of the simple structure as an elemental building block of complex metal nanostructures.


Optics Express | 2008

Near- to far-field imaging of phase evolution of light emanating from a metal nanoslit

Yun Suk Jung; Yonggang Xi; Jeff Wuenschell; Hong Koo Kim

We report near- to far-field measurement of optical wavefronts emanating from a nanoslit formed in a thin (50 nm thick) Ag film. The evolution of optical phases is imaged using a self-interference technique in conjunction with a scanning probe method. The phase relationship of the slit-transmitted waves with respect to the direct transmission through the thin metal film is quantitatively established. The singular-phase points resulting from the interplay of slit diffraction and surface plasmons are identified in the intermediate-field region.


Springer series in chemical physics | 2004

Imaging of localized silver plasmon dynamics with sub-fs time and nano-meter spatial resolution

Atsushi Kubo; Ken Onda; Hrvoje Petek; Zhijun Sun; Yun Suk Jung; Hong Koo Kim

Images of local plasmons on a silver grating excited by 400-nm, 10-fs pulses are obtained with 50-as time and 50-nm spatial resolution. The technique is based on interferometric time-resolved two-photon photoemission and photoelectron emission microscopy.

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Hong Koo Kim

University of Pittsburgh

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Palwinder Kaur

University of Pittsburgh

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Yonggang Xi

University of Pittsburgh

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Hrvoje Petek

University of Pittsburgh

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Lei Wang

University of Pittsburgh

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J. R. Blachere

University of Pittsburgh

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