Silicon Photonic Phase-Diverse Receiver Enabling Transmission of >Net 250 Gbps/λ Over 40 km for High-Speed and Low-Cost Short-Reach Optical Communications

The fast growth of data traffic in short-reach optical communications drives the demand for high-speed and low-cost optical modules. Here we demonstrate a silicon photonic (SiP) phase-diverse receiver based on our recently proposed asymmetric self-coherent detection (ASCD) scheme with Mach-Zehnder interferometers (MZI). The SiP MZI-ASCD receiver has a hardware-efficient architecture and recovers complex double-sideband signals via the beatings between a signal portion and a delayed signal portion from an asymmetric MZI using only 2 single-ended photodiodes and 2 analog-to-digital converters. The removal of the local oscillator in the direct detection receiver enables low-cost uncooled lasers, whereas the phase diversity closes the gap with coherent detection in terms of electrical spectral efficiency (ESE). Using a SiP MZI-ASCD receiver with a 15 ps delay, we detect a 60 Gbaud single-polarization 16-QAM signal transmitted over 40 km of single-mode fiber (SMF) below 20% overhead (OH) SD-FEC threshold of 2 × 10 ⁻² with a net bit rate of 200 Gbps and a record net ESE of 5.86 b/s/Hz per wavelength per polarization. Using a SiP MZI-ASCD receiver with a different delay of 7.5 ps, transmission of single-polarization 16-QAM DSB signal up to 80 Gbaud over 40 km is achieved below 24% OH SD-FEC threshold of 4.5 × 10 ⁻² with a record net bit rate of 258 Gbps and a net ESE of 5.31 b/s/Hz per wavelength per polarization.