Electro-optic comb-driven massive data transmission on monolithically integrated lithium niobate photonic circuits
Driven by large AI models, the demand for datacenter interconnects is outstripping traditional scaling laws. This necessitates a transition toward dense multiplexing techniques, such as wavelength-division multiplexing (WDM), for datacenter environments, transferring long-haul spectral efficiency to short-reach, high-bandwidth applications. Integrated optical frequency combs offer compact, low-cost light sources for future datacenter WDM interconnects. However, existing Kerr comb and mode-locked laser implementations suffer from drawbacks in power efficiency, spectral flatness and phase noise. Their fixed, device-specific channel spacings often conflict with standard WDM grids, and co-integration with high-speed modulators remains challenging. Here, we overcome these limitations by demonstrating high-capacity data transmission using flat-top electro-optic combs on thin-film lithium niobate (TFLN), a platform featuring flat spectra, tunable wavelengths and comb spacing, alongside native compatibility with (de-)multiplexers and high-speed modulators. Using 46 wavelength channels from two lasers and a 50-GHz on-chip electro-optic comb, we realize 16.56 Tb/s coherent transmission over a 98.84-km deployed fiber link between two universities and two datacenters in Hong Kong, verifying its suitability for inter-datacenter connections. To highlight grid reconfigurability, we reconfigure the comb to 100-GHz spacing via an on-chip demultiplexer and demonstrate 10-channel, 80-GBaud coherent transmission at 6.4 Tb/s. We further report a proof-of-concept monolithic WDM transmitter integrating the comb and high-speed modulator, achieving 19-channel, 45-GBaud IM/DD transmission at 1.71 Tb/s. Our work validates TFLN electro-optic combs as flexible, compact and scalable WDM engines for both coherent and IM/DD datacenter links to satisfy rapidly rising bandwidth requirements.