226.875-Gbit/s 4-PAM Operation of High-Output Power AXEL Chip on Carrier (CoC)

In this work, we propose a wire interconnection AXEL CoC designed to increase the modulation bandwidth for 200-Gbit/s/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> operation and simplify the CoC fabrication process. We first developed an electro-absorption modulator (EAM) that maintains a balance between the extinction ratio and the modulation bandwidth, and then, to increase the modulation bandwidth, we designed a termination circuit that can be integrated with the EAM and the CoC to reduce the bonding wire length. We obtained simulated 3-dB bandwidths of over 80 GHz and over 98 GHz with the longest and shortest bonding wire lengths, respectively. The 3-dB bandwidth of the AXEL CoC was over 95 GHz, which is enough for 226-Gbit/s/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda $ </tex-math></inline-formula> operation. Moreover, under 226.875 Gbit/s 4-PAM operation, the average output power exceeded +9.0 dBm thanks to the integrated SOA in the chip.