Gun-Yong Sung

Diffraction limit of the focusing waveguide grating coupler for optical probe information storage

A focusing waveguide grating coupler (FWGC) has been applied to an optical information storage element. To achieve minimum diffraction, focusing and high-coupling efficiency with high power, several fabrication and design difficulties have to be overcome. In this work, we report some new strategies to improve the fabrication and design, and greatly improve the pattern quality in defining curved gratings in the nanometre range using single-step electron-beam lithography with a conventional exposure mode. We also present the optimum fabrication conditions for the FWGC and the minimum diffraction limit (1.1 µm) obtained for the structure, which is optically the smallest diffraction spot size obtainable from diffraction gratings focusing beams into a spot in air.

Fast PCR utilizing buoyant convection in a disposable chip

We report a portable polymerase chain reaction(PCR) device conducting multiple PCR reactions in less than 5 minutes. We designed a novel loop-shaped microchannel in order to circulate PCR reactants fast through it. Temperature differences among three zones in the microchannel continuously generate a buoyant convection along the microchannel. The microchannel is molded in a disposable polymer chip. Our groups first prototype was reported previously, and we present a newly optimized device of the enhanced performance especially in PCR speed and multiplexing. The buoyant flows in the microchannel are newly visualized and compared with results from numerical simulations.

Sub-ns Dynamics of nc-Si QDs in SiNx Matrix Grown by PECVD

Time-resolved PL characteristic of the nc-Si QDs in SiNx matrix grown by PECVD is studied. The measured PL lifetime of nc-Si QDs is about 0.43 ns