Narrow-Linewidth Frequency-Agile Integrated Laser Sources Using Thin-Film Lithium Niobate

Rapid progress in the domain of integrated photonics based on thin-film lithium niobate has led to demonstrations of CMOS-voltage-compatible modulators [1], electro-optic comb generation [2] and microwave-to-optical transduction [3]. This revolution has recently reached the domain of integrated tunable lasers [4], [5]. However, the tuning rates have not been sufficient for frequency-modulated continuous-wave (FMCW) LiDAR. Here, we fill this gap by demonstrating an electro-optically tunable integrated laser source based on heterogeneous integration of lithium niobate onto a Damascene silicon nitride photonic circuit via direct wafer bonding [6]. This approach endows the passive ultra-low-loss silicon nitride circuits with electro-optic tuning capability and allows us to realize a frequency-agile laser based on lithium niobate.