Low-loss Thin Film Lithium Niobate Bonded on Silicon Nitride Waveguides

We demonstrate heterogeneous integration of thin film LiNbO 3 on Si 3 N 4 photonic integrated circuits with SiO 2 , Al 2 O 3 and direct bonding. We report record low losses in bonded ring resonators of 0.4 dB/cm (intrinsic Q = 8.19×105).