110-GHz-Bandwidth InP-HBT AMUX/ADEMUX Circuits for Beyond-1-Tb/s/ch Digital Coherent Optical Transceivers

To cope with the rapid growth of communications traffic, 400-Gb/s/ch digital coherent systems are being deployed in optical core networks. However, further scaling is required, and the transmission capacity per channel is expected to exceed 1 Tb/s in the near future to sustain the ever-growing traffic. One of the most significant challenges in achieving a channel capacity of beyond 1 Tb/s is to extend the analog bandwidth of digital-to-analog converters (DACs) and analog-to-digital converters (ADCs) in the optical transceiver. This paper describes InP-HBT-based ultra-broadband analog multiplexer (AMUX) and analog de-multiplexer (ADEMUX) circuits that can extend the analog bandwidth of DACs and ADCs, respectively. In addition, experimental demonstrations of beyond-1-Tb/s/ch optical modulations and transmissions are addressed.