Mechanical bound states in the continuum for macroscopic optomechanics

Area of Science:

• Optomechanics
• Solid-state physics
• Acoustic metamaterials

Background:

• Bound states in the continuum (BICs) are long-lived resonances observed in classical systems like photonic crystals.
• Previous research explored BICs in photonic and acoustic systems, but mechanical BICs in optomechanical crystals remain less understood.

Purpose of the Study:

• To reveal and characterize symmetry-protected mechanical BICs in slab-on-substrate optomechanical crystals.
• To analyze the coupling between mechanical BICs, optical BICs, and guided resonances.

Main Methods:

• Group theory approach to identify mechanical BICs at the Γ point in C4v and C6v symmetric optomechanical crystals.
• Numerical simulations to verify theoretical predictions and analyze optomechanical interactions.

Main Results:

• Identification of symmetry-protected mechanical BICs in optomechanical crystals.
• Analysis of coupling mechanisms including moving boundary and photo-elastic effects.
• Demonstration of substantial optomechanical interactions between mechanical BICs and optical resonances.

Conclusions:

• Slab-on-substrate optomechanical crystals host high-Q, large-size mechanical BICs.
• These systems enable substrate-enabled thermal dissipation.
• Potential applications include macroscopic quantum physics, high-throughput sensing, and free-space beam steering.