Analog Demultiplexing 128-GBd Optical Receiver Integrating a Traveling-Wave TIA and a Current-Mode Sampling Front-End

This paper presents an analog demultiplexing optical receiver capable of converting a high-baudrate optical input into two half-rate output signals, facilitating the use of lower-speed analog-to-digital converters (ADCs). This architecture not only simplifies the ADC design but also offers scalability for future high-speed receiver systems. The receiver integrates a germanium photodetector on a silicon photonic integrated circuit (PIC), a silicon germanium (SiGe) traveling-wave transimpedance amplifier (TIA), and a 4-way interleaved 256-GS/s SiGe analog demultiplexer (ADEMUX) operating in 1-to-2 mode. In order to evaluate the performance of this receiver, O-band transmission experiments were conducted at symbol rates ranging from 100 to 128 GBd for both non-return to zero (NRZ) and pulse-amplitude modulation 4-level (PAM4) modulation formats over fiber lengths up to 50 km without receiver-side digital signal processing (DSP).