Cheoljoong Kim

OSNR monitoring technique using polarization-nulling method

We report on the simple technique for monitoring the optical signal-to-noise ratios (OSNRs) of wavelength-division-multiplexed (WDM) signals. This technique, based on the polarization-nulling method, was implemented simply by using a rotating quarter-wave plate and rotating linear polarizer. However, the performance of this technique could be affected by nonlinear birefringence and polarization-mode dispersion (PMD). The result shows that this technique is suitable for monitoring the OSNRs of highspeed (>10-Gb/s) WDM signals transported over the fiber link with low PMD.

Receiver impact on first-order PMD outage

Simulation and measurement show that the robustness of a transmission system to first-order polarization-mode dispersion (PMD) depends on the combination of modulation format and receiver characteristics. For beat-noise limited receivers of typical bandwidth, return-to-zero has greater PMD tolerance than non return-to-zero coding.

2.5 Gb/s x 16-channel bidirectional WDM transmission system using bidirectional erbium-doped fiber amplifier based on spectrally interleaved synchronized etalon filters

The implemented a bidirectional erbium-doped fiber amplifier using two spectrally interleaved synchronized etalon filters. This amplifier was used to demonstrate 2.5 Gb/s/spl times/16 channel bidirectional wavelength-division-multiplexed (WDM) transmission over 160-km-long single mode fiber. No power penalty was observed in receiver sensitivity caused by relative intensity noise. In addition, we measured the performance of the concatenated amplifiers using a recirculating loop. The results show that it would be possible to use the proposed amplifier for the transmission of bidirectional WDM signals over seven amplifier spans (/spl sim/560 km) with a span loss of 20 dB.

Relative impact of multiple-path interference and amplified spontaneous emission noise on optical receiver performance

In this paper we compare the impact of MPI and ASE noise on Q-factor measurements when using an optically-preamplified receiver. We performed measurements on a 10-Gb/s data stream for two transmission formats: return-to-zero with a 50% duty cycle and a nonreturn-to-zero.

A novel bidirectional add/drop amplifier (BADA)

We demonstrate a novel bidirectional add/drop amplifier (BADA) module by using only one N/spl times/N arrayed-waveguide grating (AWG). For the effective transmission of bidirectional signals, it is essential to suppress the relative intensity noise caused by Rayleigh backscattering, multiple reflection, and/or AWG crosstalk. The proposed amplifier module can suppress the relative intensity noise simply by using two optical bandpass filters. No degradation was observed in the receiver sensitivity when these amplifier modules were used for the bidirectional transmission and add/drop multiplexing of wavelength-division-multiplexing signals.

Effects of nonlinear crosstalk in optical PMD compensation

We report on the effects of nonlinear crosstalk on the optical polarization-mode dispersion (PMD) compensation in wavelength-division-multiplexing (WDM) systems. An analytical model is presented to describe the effect of nonlinear crosstalk on the first-order PMD compensation. We also experimentally show that the performance of WDM systems could be degraded by nonlinear birefringence, even when the first-order PMD is completely compensated.

All-optical gain-controlled bidirectional add-drop amplifier using fiber Bragg gratings

We demonstrate an all-optical gain-controlled bidirectional add-drop amplifier (BADA) module by using two fiber Bragg gratings (FBGs). The proposed amplifier module could suppress the power fluctuation of the surviving channels within 0.2 dB even when thirteen out of fourteen channels were added or dropped. In addition, there was no degradation in the receiver sensitivity when this module was used for the bidirectional transmission of wavelength-division-multiplexing (WDM) signals.

Two-stage optical limiting fiber amplifier using a synchronized etalon filter

We demonstrate a two-stage optical limiting erbium-doped fiber amplifier (OLA) using an interstage synchronized etalon filter and an isolator. The proposed OLA shows higher gain, lower noise figure, and wider dynamic range (>30 dB) than conventional two-stage erbium-doped fiber amplifiers (EDFAs) with an interstage isolator. In addition, this OLA is well suited for the use in wavelength-division multiplexed (WDM) networks since the synchronized etalon filter has multiple passbands at the standardized WDM wavelengths.

Electrowetting Lenticular Lens for a Multi-View Autostereoscopic 3D Display

The multi-view autostereoscopic display has become a major form of technology for implementing 3D displaying because of its simple structure and good image characteristics compared with other methods. In particular, the lenticular type multi-view display has a higher luminance than the parallax barrier type display, which is a significant advantage. However, the lenticular lens is difficult to fabricate and uncontrollable in 2D-3D conversion. Here, we describe the fabrication of an electrowetting-based lenticular lens and a multi-view display system that utilizes that lens. With a lenticular shaped lens chamber and electrowetting liquids, the focal length of the lenticular lens can be controlled by applying voltage. By putting this device on a display panel, a 3D image can be observed with a convex lens state, and a 2D image is observed with a flat state. In this letter, an electrowetting lenticular lens is fabricated and a 2D and 3D mode switch multi-view display is demonstrated.

Depth plane adaptive integral imaging using a varifocal liquid lens array.

This paper proposes an enhanced integral imaging system with an electrically controllable image plane to address the issue of the limited depth problem in integral imaging. For implementation of the variable image plane, a varifocal liquid lens array and driving device are adopted instead of an ordinary solid lens array. The position of the central depth plane is varied by adjusting the focal length of the lens array. The proposed system enables matching between the object position and depth plane electrically, and thus an object moving from 5.15 to 11.72 cm is clearly displayed with this method.