16.85 Tb/s Coherent Communications Enabled by On-Chip Broadband Electro-Optic Frequency Combs

Chip-scale optical frequency combs (OFCs) have emerged as an attractive multiwavelength source for optical communications. Among the various types of OFC generators, electro-optic (EO) frequency combs stand out as a promising option offering high stability, simple operation, and flat comb spectra. However, data transmission performances in previous studies have been limited by the achievable comb lines due to low modulation efficiency. Here, we demonstrate terabit coherent optical communications enabled by on-chip broadband EO combs. By cascading multiple integrated modulators on a single thin-film lithium niobate chip, we generate a broadband flat-top EO comb with a comb spacing of 25 GHz and a 10 dB bandwidth of 12.4 nm. We used these 62 comb lines as the optical carriers for wavelength-division multiplexing (WDM) transmission, achieving an aggregate data rate of 12.15 Tb/s. Moreover, the chip enables the simultaneous generation of dual EO combs at different central wavelengths, expanding the total transmission capacity to 16.85 Tb/s using 86 wavelength channels. Our demonstrations highlight the potential of on-chip EO combs as WDM light sources for future high-capacity data center interconnects.