Biomedical subjects

Sunghoon Kwon

Publications and source records attributed to Sunghoon Kwon.

4 recordsLinked to original sources

PubMed2006

Magneto-optical observation of picosecond dynamics of single nanomagnets.

We report measurements of picosecond dynamics of individual nickel nanomagnets as a function of magnet dimension, aspect ratio, and magnetic environment. Spatial sensitivity to nanomagnet diameters as small as 125 nm is achieved by use of cavity enhancement of the magneto-optic Kerr effect (CE-MOKE). The importance of single-particle measurements without ensemble effects for extracting the size dependence of the intrinsic nanomagnet material properties is demonstrated.

Journal Article↗

PubMed2005

Cavity-enhanced magnetooptical observation of magnetization reversal in individual single-domain nanomagnets.

Optical studies of nanoscale magnets promise access to ultrafast magnetization dynamics but are challenging because of limited spatial resolution. We demonstrate that cavity enhancement of the magnetooptical Kerr effect increases the sensitivity in nanomagnetooptics significantly. Magnetization switching in individual single-domain magnets in both far-field and near-field Kerr microscopy is observed, and scaling laws are determined. Near-field signals remain nearly constant with reduced magnet diameter, indicating favorable scaling of near-field magnetooptics into the deep nanometer range.

Computer Simulation↗

PubMed2005

Fabrication of metallic nanodots in large-area arrays by mold-to-mold cross imprinting (MTMCI).

We have developed a mold-to-mold cross imprint (MTMCI) process, which redefines an imprint mold with another imprint mold. By performing MTMCI on two identical imprint molds with silicon spacer nanowires in a perpendicular arrangement, we fabricated a large array of sub-30-nm silicon nanopillars. Large-area arrays of Pt dots are then produced using nanoimprint lithography with the silicon nanopillar mold.

Crystallization↗

PubMed2004

Micromachined transmissive scanning confocal microscope.

We have developed a miniature scanning confocal microscope that uses electrostatically actuated microlenses for focusing and scanning. Objective lenses, scanners, a pupil, and a pinhole of the confocal microscope are microfabricated and integrated into a volume smaller than 2 mm3 by stacking these components. Objective lenses are composed of two vertically cascaded polymer microlenses integrated into micromachined comb actuators. Raster scanning is implemented by electrostatically actuating each microlens in orthogonal directions. We have demonstrated reflection confocal imaging with 3-microm transverse resolution over a 100-microm field of view and a 0.38-mm working distance at lambda = 633 nm.

Equipment Design↗