Publication

2012
Jiang Li, Hansuek Lee, Ki Youl Yang, and Kerry J. Vahala. 2012. “Sideband spectroscopy and dispersion measurement in microcavities.” Optics Express, 20, 24, Pp. 26337–26344. Publisher's VersionAbstract
The measurement of dispersion and its control have become important considerations in nonlinear devices based on microcavities. A sideband technique is applied here to accurately measure dispersion in a microcavity resulting from both geometrical and material contributions. Moreover, by combining the method with finite element simulations, we show that mapping of spectral lines to their corresponding transverse mode families is possible. The method is applicable for high-Q, micro-cavities having microwave rate free spectral range and has a relative precision of 5.5 × 10\textminus6 for a 2 mm disk cavity with FSR of 32.9382 GHz and Q of 150 milllion.
Ki Youl Yang, Vincenzo Giannini, Alexey O Bak, Hemmel Amrania, Stefan A Maier, and Chris C Phillips. 2012. “Subwavelength imaging with quantum metamaterials.” Phys. Rev. B , 86, 7. Publisher's VersionAbstract
We study the potential of a novel ``quantum metamaterial'' for subwavelength imaging applications in the midinfrared. Because the layers that comprise the metamaterial have in-plane and out-of-plane dielectric responses that are determined by different physical mechanisms (Drude free electron response and quantized electronic transitions, respectively), their resonances are polarization sensitive and can be designed independently. The result is a negatively refracting anisotropic effective medium with losses, described by the figure of meri
2010
Ki Youl Yang, Kyung Cheol Choi, Il-Suk Kang, and Chi Won Ahn. 2010. “Surface plasmon resonance enhanced photoconductivity in Cu nanoparticle films.” Opt. Express, 18, 16, Pp. 16379–16386. Publisher's VersionAbstract
We describe an all-electrical plasmon detection based on the near field coupling between plasmons and percolating electrons. It is the technique to electrically detect the local field enhancement from randomly distributed Cu nanoparticles coupled to a plasmon resonance. In addition, we revealed that plasmon-sensitivity is maximized at the percolation threshold, the minimum Cu particle surface coverage which can make the percolation path through the particles. Our detectors have a simple structure for easy fabrication and a high level of sensitivity to plasmon resonance.
2009
Ki Youl Yang, Kyung Cheol Choi, and Chi Won Ahn. 2009. “Surface plasmon-enhanced energy transfer in an organic light-emitting device structure.” Opt. Express, 17, 14, Pp. 11495–11504. Publisher's VersionAbstract
We present a surface plasmon-mediated energy transfer based on an organic light-emitting device structure. In order to localize surface plasmons, silver nano clusters were deposited thermally close to the cathode with a 1-nm-thick LiF spacer. It was shown that the surface plasmon formed on the silver nano cluster provides a strong donor decay channel and increases the donor-acceptor dipolar interaction. Thus, photoluminescence results displayed 3.5-fold enhanced acceptor emission intensity, compared with those of sample which has no Ag nano cluster.
Ki Youl Yang, Kyung Cheol Choi, and Chi Won Ahn. 2009. “Surface plasmon-enhanced spontaneous emission rate in an organic light-emitting device structure: Cathode structure for plasmonic application.” Appl. Phys. Lett., 94, 17, Pp. 173301. Publisher's VersionAbstract
The surface plasmon-enhanced spontaneous emission based on an organic light-emitting device is reported in this paper. For surface plasmon localization, silver nanoparticles were thermally deposited in a high vacuum on cathode that had a 1-nm-thick LiF spacer. Since plasmons provide a strong oscillator decay channel, time-resolved photoluminescence (PL) results displayed a 1.75-fold increased emission rate, and continuous wave PL results showed a twofold enhanced intensity. In addition, LiF film/Ag cluster/LiF film structure resolved the carrier injection problem between the cathode and the organic layer. Thus, the suggested design may follow plasmonic applications for a wider organic optoelectronics.

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