InP-Based on-Board Coherent Tx Front-End With 100-GHz Bandwidth Utilizing Flip-Chip Technology Enabling 2-Tb/s/λ Optical Transmission

We present a 100-GHz-bandwidth coherent transmitter (Tx) front-end consisting of a cost-effective PCB with a flip-chip-bonded InP-HBT-based driver IC and InP-MZM-based optical IQ modulator, which enables net 2.11- and 2.03-Tb/s/λ 80-km optical transmission. Achieving this 100-GHz bandwidth requires the use of wideband driver ICs and optical modulators as well as the implementation of a low-loss substrate and broadening the bandwidth of the interconnections between the chips and the substrate. We demonstrated the importance of such assembly technology by using a low-loss substrate with a dielectric constant of 3.06 and a dielectric loss tangent of 0.002 as the platform and flip-chip bonding, which reduces parasitic inductance, to achieve the desired wideband performance. To the best of our knowledge, this is the first demonstration of 100-GHz bandwidth and over 2-Tb/s/λ transmission using a coherent Tx front-end.