Chun-Ju Youn

Demonstration of 3×341-Gb/s PDM-OFDM-256 Iterative Polar Modulation Signals Over 495 km of a Field-Deployed WDM System

We report a field demonstration of transmission of 1.44 Tb/s over the Korean Advanced Research Network using three 341-Gb/s PDM-OFDM signals with 256-iterative-polar-modulation. The dispersion managed commercial wavelength-division multiplexed (WDM) transmission system, deployed on legacy fiber and supporting WDM transmission on a 100-GHz grid, covered the distance of 248 km between Daejeon and Seoul. Using a loop-back configuration, the three channels were transmitted over a total distance of 495 km. Successful transmission was achieved by adopting both a digital signal processing-based intersymbol-interference compensation technique and an enhanced soft-decision decoder for the coded modulation.

Real-time FPGA transmitter and receiver for coherent optical OFDM

We demonstrate a real-time FPGA implementation of coherent optical OFDM transmitter and receiver. It is implemented using two 2.5 GS/s DACs and one FPGA for transmitter, two ADCs and one FPGA for receiver, and FPGA based real-time digital signal processing for coherent optical OFDM transmission.

Hybrid-integrated coherent receiver using silica-based planar lightwave circuit technology

A hybrid-integrated coherent receiver module has been achieved using flip-chip bonding technology, consisting of a silica-based 90°-hybrid planar lightwave circuit (PLC) platform, a spot-size converter integrated waveguide photodiode (SSC-WG-PD), and a dual-channel transimpedance amplifier (TIA). The receiver module shows error-free operation up to 40Gb/s and OSNR sensitivity of 11.5 dB for BER = 10−3 at 25 Gb/s.

Cost-effective 400-Gbps micro-intradyne coherent receiver using optical butt-coupling and FPCB wirings

We present a cost-effective and bandwidth-enhanced 64-Gbaud micro-intradyne coherent receiver based on hybrid integration of InP waveguide-photodetector (WG-PD) and silica planar lightwave circuit (PLC). InP waveguide-photodetector (WG-PD) arrays are simply chip-to-chip bonded and optically butt-coupled to a silica-based dual-polarization optical hybrid chip. Multiple flexible printed circuit boards are adapted for electrical RF and DC wirings, which provide low-cost integration and good RF performance of the receiver. A 3-dB bandwidth of the fabricated coherent receiver is extended to ~36 GHz by optimization of bondwire inductance between the WG-PD array and the transimpedance amplifier (TIA), even when commercial TIAs with a typical bandwidth of ~29 GHz are used. Through optimization of the silica hybrid integrated coherent receiver, 64-Gbaud DP-16QAM signal transmission over 1050-km standard single-mode fiber is successfully demonstrated below a bit error rate of 2 × 10-3. This is the threshold for a soft decision-based forward error correction, at the optical signal to noise ratio of 23.8 dB.

Hybrid-integrated coherent receiver using silica-based PLC technology

We present a hybrid-integrated coherent receiver module using flip-chip technology for coupling a silica-based 90o-hybird planar lightwave circuit (PLC) chip to a spot-size converter integrated waveguide photodiode (SSC-WG-PD) array chip for a balanced photodiode (BPD) and interconnecting with a dual-channel transimpedance amplifier (TIA).