Piezoelectrically-Acutated Opto-Acoustic Oscillator

This paper describes the implementation of an opto-acoustic oscillator with the use of an integrated piezoelectrically-driven acousto-optic intensity modulator in aluminum nitride. Optical output collected from on-chip grating couplers is converted into the electrical domain via an avalanche photodiode, and used to drive the modulator by providing an input to its RF probing pads. Oscillation is observed at 35.2 MHz and 652.8 MHz, corresponding to peaks in the forward transmission of the modulator. An initial phase noise of -72 dBc/ Hz at 10 kHz offset from the 652.8 MHz carrier is recorded, with a large contribution from thermal noise in the amplifier chain. Some proposals for future improvements in phase noise performance are provided.