Ultra-efficient frequency comb generation in AlGaAs-on-insulator microresonators

Area of Science:

• Integrated photonics
• Nonlinear optics
• Semiconductor materials

Background:

• Dielectric platforms (Si3N4, SiO2) dominate integrated nonlinear photonics.
• Semiconductor materials offer higher nonlinearity but suffer from high waveguide losses.
• Existing limitations hinder efficient on-chip nonlinear processes.

Purpose of the Study:

• To demonstrate a low-loss AlGaAs-on-insulator platform for integrated nonlinear photonics.
• To overcome the high waveguide losses in semiconductor-based photonic devices.
• To enable efficient on-chip nonlinear optical processes with reduced power requirements.

Main Methods:

• Fabrication of an AlGaAs-on-insulator platform with anomalous dispersion.
• Achieving high-quality (Q) factors exceeding 1.5 × 10^6.
• Utilizing high nonlinear coefficient and small mode volume for nonlinear processes.

Main Results:

• Demonstrated a Kerr frequency comb generation threshold of ~36 µW, ~100 times lower than previous semiconductor platforms.
• Generated broadband combs (>250 nm) with ~300 µW pump power, surpassing state-of-the-art dielectric microcombs.
• Observed a soliton-step transition for the first time in an AlGaAs resonator.

Conclusions:

• The developed AlGaAs-on-insulator platform significantly advances integrated nonlinear photonics.
• Low-loss, high-Q AlGaAs enables highly efficient on-chip nonlinear optical phenomena.
• This platform paves the way for next-generation integrated photonic devices and applications.