Subwavelength engineering for Brillouin gain optimization in silicon optomechanical waveguides

Area of Science:

• Photonics
• Optomechanics
• Materials Science

Background:

• Brillouin optomechanics offers new silicon photonics functionalities like opto-RF processing.
• Maximizing photon-phonon interaction and phonon lifetime is crucial but challenging.

Purpose of the Study:

• To propose a novel strategy for maximizing Brillouin gain in silicon waveguides.
• To exploit subwavelength engineering for enhanced optomechanical performance.

Main Methods:

• Designing subwavelength periodic structures in silicon membrane waveguides.
• Theoretically analyzing the confinement of near-infrared photons and GHz phonons.
• Minimizing optical and mechanical losses.

Main Results:

• Achieved tight confinement of photons and phonons, maximizing Brillouin coupling.
• Predicted a high mechanical quality factor (up to 700).
• Predicted a remarkable Brillouin gain of 3500 (W·m)⁻¹ with 50 nm feature size.

Conclusions:

• Subwavelength engineering effectively enhances Brillouin optomechanical interactions in silicon.
• The proposed waveguide design is compatible with electron-beam lithography.
• This approach holds significant potential for future silicon photonics applications.