Wangjoo Lee

Real-time continuous-wave terahertz line scanner based on a compact 1 × 240 InGaAs Schottky barrier diode array detector

We demonstrate real-time continuous-wave terahertz (THz) line-scanned imaging based on a 1 × 240 InGaAs Schottky barrier diode (SBD) array detector with a scan velocity of 25 cm/s, a scan line length of 12 cm, and a pixel size of 0.5 × 0.5 mm². Foreign substances, such as a paper clip with a spatial resolution of approximately 1 mm that is hidden under a cracker, are clearly detected by this THz line-scanning system. The system consists of the SBD array detector, a 200-GHz gyrotron source, a conveyor system, and several optical components such as a high-density polyethylene cylindrical lens, metal cylindrical mirror, and THz wire-grid polarizer. Using the THz polarizer, the signal-to-noise ratio of the SBD array detector improves because the quality of the source beam is enhanced.

40GHz clock generation using clock component enhancement modulation and band pass filtering

The applicability of clock and data superposed modulation for clock component enhancement In 40Gb/s NRZ signal was experimentally demonstrated. From this slgoal 40GHz clock was easily extracted by hand-pass filtering. The result showed 0.5dB power penalty Improvement with respect to a conventional clock extraction method of using noo-linear circuits. It is also pointed out that relative amplitude and phase of the two superposed modulation signals are very Important for good BER characteristics.

Simple CNT nanocomposite piezoresistive press sensor

Flexible piezoresistive press sensor where CNT nanocomposite is dispersed in PDMS matrix is fabricated using a simple CNT mixing method. The sensor showed resistance sensitivity up to 43.75kPa and maximum of 10% hysteresis. It showed resistance reduction effect after some press stresses that might be related to the squeezing effect of the PDMS matrix. Also it showed resistance drift under constant pressure needing for improvement of mechanical characteristic and supplementing signal processing.