Amplification-free 240 Gbps optical interconnection with TFLN transmitter and Ge-PD receiver

The exponential growth of data traffic in modern data centers has driven the demand for ultra-high-bandwidth, low-power optical interconnects. While 200 Gbps per wavelength has become standardized, next-generation systems aim to exceed this benchmark without relying on power-hungry digital signal processors (DSPs). Leveraging the CMOS compatibility and scalability of germanium photodetectors (Ge-PDs) over traditional III-V-based counterparts, we report, for the first time, to the best of our knowledge, a 240-Gbps O-band optical interconnect over 2 km of standard fiber without any DSP and amplification in both optical and electrical domains. This demonstration employs a >70 GHz thin-film lithium niobate (TFLN) modulator and a 91 GHz Ge PD, establishing a viable path toward compact, energy-efficient, and high-speed heterogeneous integration for future optical transceivers.