Integrated Self-Coherent Optical Transceivers for Data Center Applications Based on Thin-Film Lithium Niobate Platform

In this work, we demonstrate the first proof-of-concept integrated self-coherent optical transceiver on thin-film lithium niobate (TFLN), leveraging a high-speed electro-optic modulator at the transmitter, and an on-chip dynamic polarization controller (DPC) at the integrated self-coherent receiver. The dual-fiber self-coherent architecture transmits a dual-polarization (DP) 56-Gbaud 16-QAM signal over 20 km of fiber, while the receiver's DPC stabilizes the carrier's state of polarization, enabling robust self-homodyne detection despite rapid polarization drift. Experimentally, the polarization control loop tracks SOP rotations up to 400 krad/s while maintaining a bit-error ratio (BER) below the hard-decision forward-error-correction threshold of 3.8 × 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup>. These results indicate that TFLN integrated photonics can effectively bridge the gap between simple IM/DD systems and high-spectral-efficiency coherent links, offering a promising path toward compact, low-power, and high-performance optical interconnects for next-generation data centers.