Waveguide-coupled photonic crystal cavity for quantum dot spin readout.

Area of Science:

• Photonics
• Optical Cavities
• Quantum Information Science

Background:

• Photonic crystal cavities offer unique light-matter interaction properties.
• Efficiently coupling cavity modes to external waveguides is crucial for device applications.
• H1 cavities are known for their high quality factors and potential for mode control.

Purpose of the Study:

• To design and demonstrate a waveguide-coupled photonic crystal H1 cavity.
• To achieve efficient and spatially separated coupling of orthogonal dipole modes.
• To explore potential applications in quantum information processing and optical switching.

Main Methods:

• Fabrication of a photonic crystal H1 cavity structure.
• Integration of two spatially separated photonic crystal waveguides.
• Precise adjustment of waveguide position and orientation for optimized coupling.
• Experimental verification of coupling efficiency and device behavior.

Main Results:

• Demonstrated efficient coupling of orthogonal dipole modes to separate waveguides.
• Achieved coupled Q-factors up to 1600.
• Obtained contrast ratios up to 10.
• Verified device performance for cavity mode splitting both larger and smaller than the cavity linewidth.

Conclusions:

• The developed waveguide-coupled H1 cavity structure enables controlled light coupling.
• This design shows promise for spin state readout of quantum dots.
• The device may function as an ultra-fast optical switch at the single-photon level.