심장섭 교수

A hybrid wavelength-division-multiplexed/time-division-multiplexed passive optical network serving 128 subscribers with wavelength-selection-free transmitters is presented by cascading 1/spl times/16 arrayed-waveguide gratings (AWGs) and 1/spl times/8 splitters. The wavelength-selection-free transmitter is an uncooled Fabry-Pe/spl acute/rot laser diode (FP-LD) wavelength-locked to an externally injected narrow-band amplified spontaneous emission (ASE). Bit-error rates better than 10/sup -9/ over

This paper presents a low-cost bidirectional (BiDi) wavelength-division-multiplexed passive optical network (WDM-PON) employing colorless uncooled BiDi transceivers (TRxs) and superluminescent diode (SLD)-based broadband light sources (BLSs). The C band is allocated for upstream and the E+ band for downstream in consideration of BiDi packaging, SLD development, and wavelength alignment of dual-window arrayed waveguide gratings (AWGs). The BiDi TRx integrates an uncooled Fabry-Perot laser diode (

Cascadable active laser logic devices are described, demonstrating NOR and INVERTER functions with a negative optical gain of five. The surface-emitting laser logic device consists of an AlGaAs superlattice surface-emitting laser discretely connected to an AlGaAs heterojunction phototransistor in parallel. The optical logic output of 0.5 mW is controlled off with 100 mu W incident power (44 mu W absorbed) on the heterojunction phototransistor part of the device.< <ETX xmlns:mml="http://www.w3.or

An optical fault monitoring method in WDM-PON using a broadband light source is demonstrated. This method can achieve real-time fault monitoring for WDM channels. In addition, the optical line terminal can distinguish transmission fibre fault from upstream transmitter failure in the optical network unit.

An angle-tuned Fabry-Perot (FP) filter is used to obtain bandwidth optimized multichannels from the amplified spontaneous emission generated from a fiber amplifier light source. Rotating the FP filter, we change the channel bandwidth for a wide range making use of a small angular spread of an incident beam while nearly unaffecting the channel spacing. The output power is made insensitive to the rotation of the FP filter using a double-stage fiber amplifier structure with the FP filter placed bet

We demonstrate a gain-clamped semiconductor optical amplifier (GC-SOA) which has gratings under both end regions of an active waveguide. Two gratings of the new GC-SOA are fabricated in different lengths. Their lasing modes and gain characteristics are measured and analyzed with different combinations of grating lengths. It shows different gain and noise characteristics according to the measurement direction in asymmetric grating combinations.

We propose a 1-fiber bidirectional WDM self-healing ring that has bidirectional optical add/drop multiplexers. A simple fault detection method is proposed, and no signal degradation due to in-band crosstalk is demonstrated in the failure state. The power penalty of the ring transmission was less than 1 dB at a BER 10/sup -12/ in the normal and failure state.

We present a low-cost C/S-band WDM-PON employing colorless uncooled bidirectional transceivers and SOA-based broadband light sources. Colorless operations over 32 DWDM channels are demonstrated from -20 to 80/spl deg/C in 155-Mb/s bidirectional transmissions over 25 km.

The total input noise current and sensitivity of the fiber-optic receiver was calculated. The flicker noise source was included by adopting a pertinent flicker noise model. Power penalties caused by the flicker noise were calculated for various fiber-optic receivers using the calculated noise current. It has been found that the flicker noise affects the sensitivity over the whole range of the bit rates, and that the total input capacitance is an important parameter affecting the power penalty wh

BACKGROUND: Automatic cell tracking methods enable practitioners to analyze cell behaviors efficiently. Notwithstanding the continuous development of relevant software, user-friendly visualization tools have room for further improvements. Typical visualization mostly comes with main cell tracking tools as a simple plug-in, or relies on specific software/platforms. Although some tools are standalone, limited visual interactivity is provided, or otherwise cell tracking outputs are partially visual

We propose and demonstrate a cost-effective way to implement a 10-Gb/s chirped duobinary (CDB) transmitter using an electroabsorption modulated laser (EML) followed by a LiNbO/sub 3/ Mach-Zehnder modulator both driven with binary signals. Successful transmission is achieved over 285 km of dispersion-uncompensated standard single-mode fiber without significantly increasing the complexity and cost of the transmitter, compared to conventional duobinary transmitters. The demonstrated CDB signals exh