Slot-mode cantilever optomechanical system for mass sensing

Area of Science:

• Optomechanics
• Nanotechnology
• Materials Science

Background:

• Optomechanical systems leverage light-matter interactions for sensing.
• High-sensitivity mass sensing is crucial for various scientific disciplines.
• Photonic crystal cavities offer strong light confinement for enhanced interactions.

Purpose of the Study:

• To present a novel slot-mode optomechanical platform integrating a photonic crystal cavity and a cantilever resonator.
• To achieve high optomechanical coupling and low effective mass for sensitive mass sensing.
• To explore the potential for sub-zeptogram mass sensitivity.

Main Methods:

• Fabrication of devices using silicon-on-insulator substrates.
• Integration of a one-dimensional photonic crystal cavity with a cantilever mechanical resonator.
• Characterization using thermomechanical noise analysis and phase-locked loop frequency tracking.

Main Results:

• Demonstrated high optomechanical coupling (G/2π = 0.80 GHz/nm) and low effective mass (m_eff = 13 fg).
• Achieved an estimated mass sensitivity of approximately 30 zeptograms (zg).
• Identified temperature-driven cavity frequency fluctuations as a dominant noise source.

Conclusions:

• The cantilever-based slot-mode optomechanical platform offers enhanced dynamic range and reduced mass compared to traditional designs.
• The demonstrated sensitivity approaches the zeptogram scale, with potential for sub-zeptogram levels.
• Future improvements in optomechanical coupling and cavity quality factor are key to reaching sub-zeptogram sensitivity.