Ultrasensitive nanoscale optomechanical electrometer using photonic crystal cavities

Area of Science:

• Nanophotonics
• Optomechanics
• Precision Sensing

Background:

• High-precision electric charge detection is crucial for physical, chemical, and biological applications.
• Nanophotonic optomechanical systems offer strong light-matter interaction for enhanced sensing capabilities.

Purpose of the Study:

• To propose and demonstrate an integrated optomechanical electrometer for ultrasensitive electric charge sensing.
• To leverage a zipper cavity and photonic crystal nanobeam for precise voltage and charge measurements.

Main Methods:

• Utilized a suspended photonic crystal nanobeam as a movable mechanical resonator within a zipper cavity.
• Employed optomechanical coupling to transduce mechanical motion, modulated by electrostatic forces, into optical signals.
• Operated the system in self-sustained oscillation above threshold power to enhance sensitivity.

Main Results:

• Achieved a voltage sensitivity of 0.007 V and an enhanced electrical sensitivity of 0.014 V.
• Demonstrated a high resolution and a peak-to-noise floor ratio of up to 73.5 dB in the radio frequency spectrum.
• Calculated a theoretical minimal detectable electrostatic charge of 1.2 e⁻/√Hz.

Conclusions:

• The proposed on-chip optomechanical electrometry scheme offers a powerful solution for ultrasensitive determination of charged nanoparticles.
• This technology has significant potential for advancements in biological and chemical sensing applications.