X-Band Aom on Chip

Silicon Nitride integrated photonic circuits have drawn much attention owing to its ultra-low loss and large Kerr nonlinearity. However, the lack of Pockels effect makes it difficult to be modulated electro-optically, which posts a major challenge for the further development of Si
₃
N
₄
circuits with advanced functions. The widely adopted thermo-optical tuning suffers from large power consumption and restricted speed (~1 kHz). In this study, microwave frequency modulation (up to 9 GHz) of Si
₃
N
₄
ring resonator is achieved by exciting bulk acoustic waves piezoelectrically, which modulates the microring via stress-optical effect. The acoustic waves are confined tightly in a released SiO
₂
thin film which enhances the acoustic energy density and thus modulation efficiency.