Strong Cavity-Optomechanical Transduction of Nanopillar Motion

Area of Science:

• Nanophotonics and Optomechanics
• Materials Science and Engineering
• Biosensing and Force Transduction

Background:

• Nanomechanical resonators are ideal for ultrasensitive force sensing but face transduction challenges.
• Vertical structures like nanopillars are promising but require efficient light confinement for optical transduction.
• Existing photonic crystal (PhC) designs struggle with effective vertical light confinement.

Purpose of the Study:

• To present a novel full-silicon photonic crystal cavity platform based on specifically designed nanopillars.
• To enable efficient optical transduction of nanomechanical motion for force and biosensing applications.
• To overcome limitations in vertical light confinement for high-quality PhC cavities.

Main Methods:

• Fabrication of a silicon photonic crystal cavity using a unit cell with a top-larger-diameter nanopillar design.
• Experimental demonstration of optical cavities with quality (Q) factors exceeding 10^3 by introducing defects.
• Characterization of the optomechanical (OM) properties of the nanopillar-based cavities.

Main Results:

• Achieved vertical light confinement and an energy band gap in the near-infrared for transverse-magnetic polarization.
• Demonstrated experimental Q factors > 10^3, indicating high-quality optical cavities.
• Confirmed that each nanopillar acts as a nanomechanical cantilever, enabling optical transduction of motion.

Conclusions:

• The developed nanopillar-based PhC cavities provide an effective platform for optomechanical sensing.
• These cavities offer enhanced mechanical properties, cost-effectiveness, and scalability compared to traditional designs.
• This technology presents a viable alternative to silicon-on-insulator (SOI) based suspended silicon beam optomechanical cavities.