Hybrid SiO₂/Si pillar-based optomechanical crystals for on-chip photonic integration

Area of Science:

• Photonics
• Optomechanics
• Nanotechnology

Background:

• One-dimensional photonic crystal (1D-PhC) pillar cavities enable mechanical vibration transduction to the optical domain.
• Existing methods for mechanical motion detection have stringent requirements.
• Silicon-on-insulator (SOI) photonics offers a robust platform for integrated devices.

Purpose of the Study:

• To integrate 1D-PhC pillar cavities into an SOI platform.
• To explore the optical and mechanical properties of these integrated structures.
• To enhance mechanical motion transduction for MEMS and NEMS applications.

Main Methods:

• Fabrication of 1D-PhC structures with high aspect ratio nanopillars.
• Engineering of integrated waveguides for transverse-magnetic (TM) polarized light.
• Finite element method (FEM) simulations and experimental analysis.
• Tuning the separation between 1D-PhC and waveguide for optimal coupling.

Main Results:

• Achieved high optical quality factors (Q ~ 4 × 10^3).
• Demonstrated optomechanical coupling rates exceeding 1 MHz for fundamental modes.
• Enabled transduction of mechanical modes from tens to hundreds of MHz.
• Optimized optical coupling via waveguide-cavity interaction.

Conclusions:

• The integrated 1D-PhC cavities effectively transduce mechanical vibrations to the optical domain.
• Enhanced optomechanical coupling rates and broad frequency transduction improve MEMS/NEMS viability.
• These findings advance applications in force sensing and biosensing.