Ultra-low loss large-scale photonic integrated circuits on thin film lithium niobate

Low-loss large-scale photonic integrated circuits (PICs) combined with highly efficient electro-optic (EO) tuneability offers tremendous opportunities for developing high-performance and highly functional photonic devices and systems. In comparison with the fiber-based devices, large-scale PICs can potentially be more compact, more power efficient, and more cost-effective. On the other hand, large-scale PICs can also be potentially used for optical computation and photonic neural network applications. To realize large-scale PICs, we develop photolithography assisted chemo-mechanical etching (PLACE) and apply it for fabricating PICs on thin-film lithium niobate (TFLN). We then demonstrate various kinds of PICs ranging from low-loss optical delay lines and photonic neural network to EO tunable lasers and high-power waveguide amplifiers. Significant improvements have been achieved with respect to the key parameters/performances of TFLN photonics devices, such as modulation bandwidth, power consumption, propagation loss, active and passive functionalities, and scale of integration.