Decoupled Characterization of Electro-opto-mechanical Transduction - Leveraging Pull-in Hysteresis in NEMS Photonic Modulators.

Integration of nano-electromechanical systems (NEMS) actuators into multi-physics platforms, such as with photonic integrated circuits (PICs), can provide unique advantages in power consumption, form factor, and performance. However, characterization of these systems is challenging due to their coupled transduction mechanisms. This paper discusses the interactions between electro-mechanical and opto-mechanical transduction in nano-scale photonic modulators. Herein, pull-in instability and spring softening is leveraged as a self-characterization mechanism within a novel high-sensitivity NEMS actuator that is monolithically integrated with a photonic resonator. Through this method, measurements using existing input/output (I/O) connections to the device can provide new insights into internal device interactions between the electrical, optical, and mechanical domains. This study shows a novel demonstration of the measurement of optical force effects generated between the photonic resonator and the NEMS actuator. Extraction of the electro-mechanical actuation shows that the device achieves an order of magnitude enhancement in mechanical sensitivity (> 550 nm/V) over the state-of-the-art by using a non-linear electrostatic design while maintaining the optomechanical performance compared to previous high quality-factor (Q > 10 k) monolithic devices. This study provides new experimental approaches for extracting photonic NEMS parameters and serves as a model for characterizing other multi-physics systems.