Integrated lithium niobate microwave photonics: Driving next-generation wireless technologies

Abstract: Integrated microwave photonics (MWP) offers a powerful paradigm for handling high-speed microwave signals within chip-scale optical systems. It provides a cost-effective solution to address bandwidth, tunability, and loss bottlenecks of electronics-based radio frequency (RF) systems. The recently emerged thin-film lithium niobate (TFLN) photonic platform, with its exceptional electro-optic (EO) properties, low loss, and scalability, has shown promise to reshape the MWP landscape. Here, we discuss the performance implications of state-of-the-art TFLN photonic devices for MWP applications and offer insights into the emerging trends for next-generation wireless networks. In particular, the unparalleled EO bandwidth enables direct optical generation, processing, and reception of millimeter-wave or even terahertz (THz) signals, significantly expanding the operation frequency range of MWP systems. The low drive voltages and linearity of TFLN modulators lead to an unprecedented operation regime of radio-over-fiber (RoF) systems, featuring net gain, low noise figure and large dynamic range, simultaneously. The availability of a versatile device toolkit, combined with low optical loss and scalability, further supports the transition from traditional tabletop MWP systems to chip-scale solutions, with advanced functionalities, compact footprint, and enhanced system robustness. As the TFLN industrial ecosystem rapidly matures, TFLN-based MWP technology has the potential to deliver transformative solutions to future 6G integrated sensing and communication networks.