Sub-Hz Closed-Loop Electro-Optomechanical Oscillator with Gallium Phosphide Photonic Crystal Integrated on SoI...

Area of Science:

• Photonics
• Optomechanics
• Materials Science

Background:

• Optomechanical oscillators are crucial for advanced sensing and communication.
• Achieving low phase noise and GHz operation in integrated systems remains a challenge.

Purpose of the Study:

• To report a new approach for a low phase noise electro-optomechanical oscillator operating directly in the GHz frequency range.
• To demonstrate the feasibility of integrated optomechanical oscillators for future microwave applications.

Main Methods:

• Fabrication of a one-dimensional photonic crystal nanoscale oscillator using gallium phosphide (GaP) heterogeneously integrated on silicon-on-insulator (SOI).
• Utilizing strong optomechanical interaction between optical and GHz mechanical modes.
• Implementing a delayed optoelectronic feedback loop with integrated electro-mechanical self-injection for stabilization.

Main Results:

• Achieved ultra-pure mechanical oscillations directly imprinted on an optical carrier.
• Demonstrated a short-term stability with a 0.7 Hz linewidth.
• Attained a long-term stability with an Allan deviation below 10^-7 Hz/Hz at 10 s averaging time.

Conclusions:

• The developed integrated optomechanical oscillator represents a significant advancement toward fully on-chip solutions.
• The low phase noise and integrability address key needs for optoelectronic oscillators.
• This technology paves the way for on-chip integrated microwave oscillators for applications like RADARs.