Silicon-photonics transmitter using ultra-wideband quantum-dot comb laser-diode towards 34.132 Tbit/s/fiber.

A key challenge in current silicon photonics (SiPh) optical transceiver (TRx) and optical engine is achieving sufficiently high bandwidth density within the limited footprint. In this work, we present a proof-of-concept demonstration of a high-capacity optical transmitter (Tx) that integrates four SiPh-based Mach-Zehnder modulators (MZMs), an O-band ultra-wideband quantum-dot comb laser diode (QDLD), and a multi-core fiber (MCF), enabling simultaneous multiplexing in both wavelength and spatial domains. The QDLD comb laser source generates a large number of evenly spaced, phase-coherent wavelength channels from a single device, eliminating the need for multiple discrete lasers and simplifying system complexity. In the proof-of-concept experiments, repeated measurements are performed for each comb line to ensure statistical reliability. Each comb line is modulated using four-level pulse amplitude modulation (PAM4) at a data rate of 212 Gbit/s. By utilizing 23 comb lines with sufficient signal-to-noise ratio (SNR), in combination with seven spatial cores in an MCF, the system could achieve an aggregate data rate of up to 34.132 Tbit/s (212 Gbit/s × 23 comb lines × 7 cores). The average transmitter-dispersion-eye-closure-quaternary (TDECQ) is within 2.02 dB after 2 km of fiber transmission.