VLSI Piezoelectric Optomechanics for GHz Reference Oscillators

Oscillators based on optomechanical micro-resonators have emerged as a high-performance alternative for GHz time references, but their integration with compact electronics remains a challenge. Current implementations present either off-chip actuation of the resonators or inefficient on-chip methods requiring important actuation voltages, both incompatible with integrated electronics. Here we present an alternative based on piezoelectric (AlN) optomechanics, providing state-of-the-art phase noise (−105 dBclHz @ 10 kHz for a carrier at 280 MHz) with an actuation voltage of only 100 mV. The demonstrator was fabricated with a VLSI technology specifically developed for sensors and reference oscillators in a semi-industrial clean room.