Cavity-resonator integrated bi-atom grating coupler for enhanced second-harmonic generation

Area of Science:

• Photonics
• Nonlinear Optics
• Integrated Optics

Background:

• Second-harmonic generation (SHG) is crucial for frequency conversion in photonics.
• Integrated photonic devices require efficient and manufacturable light-matter interaction structures.
• Existing grating couplers often face trade-offs between efficiency, Q-factor, and fabrication complexity.

Purpose of the Study:

• To design cavity-resonator integrated grating couplers for efficient second-harmonic generation.
• To achieve high Q-factors with a fabrication-friendly approach.
• To demonstrate competitive conversion efficiencies for integrated photonic applications.

Main Methods:

• Utilizing a bi-atom ridge pattern for grating coupler design.
• Integrating grating couplers with cavity-resonators and distributed Bragg reflectors (DBR).
• Numerical simulations to optimize parameters and evaluate performance, including conversion efficiency and transition losses.

Main Results:

• Achieved extremely high Q-factors (above 10^5) with the bi-atom grating coupler design.
• Demonstrated numerical conversion efficiencies of several tenths per Watt.
• Showcased doubled efficiencies by incorporating a phase-matching grating.
• Minimized transition losses between grating coupler and DBR sections through careful parameter selection.

Conclusions:

• The proposed cavity-resonator integrated grating couplers offer a promising route for efficient on-chip second-harmonic generation.
• The bi-atom design provides a balance between high performance (high Q-factor, high efficiency) and fabrication feasibility.
• These structures present a competitive alternative to waveguides and nano-resonators for SHG applications in integrated photonics.