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Your search keyword '"Chung, Y-C"' showing total 98 results
Start Over Author "Chung, Y-C" Publisher ieee
98 results on '"Chung, Y-C"'

2. 300-Gb/s Transmission Using OTDM System Implemented With Sinusoidally Modulated Input Light Source.

Author

Kim, M. S., Kim, B. G., and Chung, Y. C.

Abstract

The recently proposed 2-channel optical-time-division-multiplexing (OTDM) technique utilizing a sinusoidally modulated input light source provides an attractive solution to double the per-wavelength data rate of the short-reach intensity-modulation/direct-detection system. However, to maximize the transmission speed of such an OTDM system, it is necessary to generate the sinusoidal input light operating at the frequency much faster than the modulator’s bandwidth. As a result, the extinction ratio (ER) of the generated sinusoidal input light can be significantly reduced, which, in turn, causes a large crosstalk in this OTDM system. To solve this problem, we propose to enhance the ER of the sinusoidal input light simply by decreasing the bias voltage applied to the Mach-Zehnder modulator (MZM) used for its generation (from the quadrature point toward the null point). We estimate that, by using this technique, it is possible to increase the ER from 3.1 dB to 14.9 dB when the required sinusoidal frequency is three times faster than the MZM’s bandwidth. To verify the effectiveness of this ER enhancement technique, we realize the 2-channel OTDM system with a sinusoidally modulated input light source by using the MZMs having a 3-dB bandwidth of 17.2 GHz and demonstrate the transmission of the 300-Gb/s PAM8 signal. Thus, the ratio between the achieved data rate and the 3-dB bandwidth of the MZM is as high as ~17.4. [ABSTRACT FROM AUTHOR]

Published
2022
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9. Effects of External Optical Feedback on PAM4 Signal in VCSEL-Based SMF Link.

Author

Kim, M. S., Kim, B. G., Bae, S. H., and Chung, Y. C.

Abstract

We evaluate the effects of the external optical feedback on the on-off keying (OOK) and four-level pulse amplitude modulation (PAM4) signals in the single-mode fiber (SMF) link implemented by using a commercial 10G-class 1.55- $\mu \text{m}$ vertical-cavity surface-emitting laser (VCSEL). The results show that the PAM4 signal is much more sensitive to the external optical feedback than the OOK signal. For example, in the back-to-back condition, an error floor is observed at the bit-error rate (BER) of $\sim 8\times 10 ^{\mathbf {-3}}$ for the 10-Gbaud PAM4 signal when we set the optical feedback ratio to be −14 dB. In comparison, the 10-Gbaud OOK signal has a power penalty of only 0.4 dB (@BER $= 5\times 10 ^{-5}$) under the same conditions. The results also show that the PAM4 signal becomes more sensitive to the optical feedback after the SMF transmission due to the shallowed BER curve by the fiber dispersion. In addition, we confirm that the effects of the optical feedback are independent of the baud rate. From these results, we conclude that the error-free transmission of the high-speed PAM4 signal cannot be achieved if there is even one bad fiber connector having >2.5% reflection in the VCSEL-based SMF link. [ABSTRACT FROM AUTHOR]

Published
2020
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14. Effects of Multi-Level Format in MMF System Based on Mode-Field Matched Center-Launching Technique.

Author

Kim, M. S., Kim, B. G., Bae, S. H., and Chung, Y. C.

Abstract

We evaluate the performances of 25.78-Gb/s signals modulated in on–off keying and four-level pulse amplitude modulation (PAM4) formats in the 12.2-km long multi-mode fiber (MMF) transmission system implemented by using the mode-field matched center-launching technique, which is realized simply by fusion-splicing the single-mode fiber (SMF)-pigtailed transceivers to the transmission MMF. The results show a serious bit-error rate (BER) fluctuation as well as a large power penalty for the PAM4 signal after the 12.2-km long MMF transmission. We identify that the power penalty and BER fluctuations are caused by the signal-to-interference beat noise generated in the SMF-pigtailed receiver, resulting from the small portion of the signal (~5%) unwantedly carried by the high-order modes of MMF. However, we can suppress this beat noise by replacing the SMF-pigtailed receiver with the MMF-pigtailed one since all modes are orthogonal in MMF. For example, when we utilize this proposed method, the power penalty of the 25.78-Gb/s PAM4 signal measured after the transmission over 12.2 km of MMF is reduced from 3.9 to 0.9 dB (@ BER $= 5\times 10^{-5}$). We also demonstrate the transmission of the 56-Gb/s PAM4 signal over 2.3 km of MMF by using this method. [ABSTRACT FROM AUTHOR]

Published
2018
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