Comb‐Driven Coherent Optical Transmitter for Scalable DWDM Interconnects

ABSTRACT Next‐generation large‐scale artificial intelligence systems are poised to exceed the capacity of current optical interconnect technologies. This surge imposes stringent constraints on transmitter scalability and integration compatibility. A comb‐driven coherent optical transmitter architecture on a Si/SiN platform is presented to address these challenges by combining dense wavelength‐division multiplexing (DWDM) and coherent signaling within a unified framework. Scalability is validated through the design and experimental demonstration of key building blocks, including ultra‐compact microring‐based coherent modulators and DWDM interleavers, enabling high‐baud‐rate operation and efficient wavelength management. Single‐tone experiments demonstrate a net line rate of 400 Gb/s per polarization (16‐QAM, 120 GBaud) in the O‐band, achieving a shoreline bandwidth density of 4 Tb/s/mm. Transmission at up to 160 GBaud QPSK in back‐to‐back and 100 GBaud over 7 km of fiber without dispersion compensation is also demonstrated. Multi‐wavelength operation is further validated using a quantum‐dot frequency comb, enabling sequential transmission across six 100 GHz‐spaced channels and achieving an aggregated net rate of 1.08 Tb/s over 5 km. System‐level analysis indicates that the architecture can support aggregate rates exceeding 10 Tb/s per fiber within practical power and packaging constraints, outlining a viable path toward petabit‐scale interconnects.