Dr. Kunik Lee Profile

Dr. Kunik Lee

at Federal Highway Administration-TFHRC

SPIE Involvement:

Author

Proceedings Article | 31 March 2012 Paper

Wireless power using magnetic resonance coupling for neural sensing applications

Hargsoon Yoon, Hyunjung Kim, Sang Choi, Larry Sanford, Demetris Geddis, Kunik Lee, Jaehwan Kim, Kyo Song

Proceedings Volume 8344, 83440S (2012) https://doi.org/10.1117/12.917650

KEYWORDS: Magnetism, Sensing systems, Inductive coupling, Magnetic sensors, Brain, Animal model studies, Signal processing, Data communications, Systems modeling, Receivers

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Proceedings Article | 31 March 2012 Paper

Effect of rare earth elements (Er, Ho) on semi-metallic materials (ScN) in an applied electric field

Hyunjung Kim, Yeonjoon Park, Glen King, Kunik Lee, Sang Choi

Proceedings Volume 8344, 83440X (2012) https://doi.org/10.1117/12.917313

KEYWORDS: Erbium, Transmission electron microscopy, Holmium, Absorption, Crystals, Electrons, Refractive index, Thin films, Spectroscopy, Electron beams

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The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare earth elements, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare earth elements (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV (±0.2eV) respectively. This is less than that of undoped ScN (2.5±0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (E_g), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM analysis. These results give an insight for future applications for the field-controlled spectrally active material

Proceedings Article | 31 March 2012 Paper

Thermal effects of X-band microwaves on skin tissues

Kyo Song, Hargsoon Yoon, Kunik Lee, Jaehwan Kim, Sang Choi

Proceedings Volume 8344, 834418 (2012) https://doi.org/10.1117/12.917620

KEYWORDS: Microwave radiation, Skin, Tissues, Dielectrics, Absorption, Thermal effects, Sensors, Near field, Distance measurement, Brain

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Proceedings Article | 15 April 2011 Paper

Near field effects of millimeter-wave power transmission for medical applications

Hargsoon Yoon, Kyo Song, Kunik Lee, Jaehwan Kim, Sang Choi

Proceedings Volume 7980, 798012 (2011) https://doi.org/10.1117/12.880526

KEYWORDS: Antennas, Near field, Wireless energy transfer, Skin, Distance measurement, Microwave radiation, Absorption, Biomedical optics, Diodes, Transceivers

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Proceedings Article | 14 April 2011 Paper

X-ray diffraction wafer mapping method for SiGe twin defects characterization

Yeonjoon Park, Hyunjung Kim, Glen King, Kunik Lee, Sang H. Choi

Proceedings Volume 7980, 79800T (2011) https://doi.org/10.1117/12.880578

KEYWORDS: Crystals, Semiconducting wafers, Sapphire, X-rays, Epitaxy, X-ray diffraction, Group IV semiconductors, Diamond, Semiconductors, Silicon

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Proceedings Article | 22 April 2010 Paper

Versatile smart optical material characterizer system

Yeonjoon Park, SangJoon Park, Uhn Lee, Kunik Lee, Sang Choi

Proceedings Volume 7646, 764613 (2010) https://doi.org/10.1117/12.852774

KEYWORDS: Liquid crystals, Optical testing, Control systems, Optical components, Refractive index, Phase measurement, Polarization, Optical properties, Chemical elements, Electro optics

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