Programmable Silicon Nitride Photonic Integrated Circuits

Silicon Nitride (Si3N4) photonic integrated circuits (PICs) have emerged as core technology in a variety of applications ranging from LIDAR to quantum control and computing. However, the need for high-speed, low-voltage tuning and modulation has been a long standing challenge because Si3N4 lacks electro-optic effect. In this work, we demonstrate power efficient (nW) and fast (sub-mu s) piezoelectric tuning of Si3N4 optical microring resonators by monolithically integrating Lead Zirconate Titanate (PZT) piezoMEMS actuators. We achieve, for the first time, the co-integration of PZT and thermal actuators, enabling the tuning of optical resonances over one free spectral range (FSR). The programmability is demonstrated by aligning two optical resonators fabricated on separate chips, which is the first step towards fiber-optic connected optomechanical sensors and computing networks. We further show acousto-optic modulation (AOM) of Si3N4 photonics using the High-overtone Bulk Acoustic Resonators (HBAR) excited by PZT actuators with modulation frequency up to 2 GHz.