Silicon-photonics-compatible optomechanical oscillator operating in the low-megahertz regime

Area of Science:

• Integrated photonics
• Optomechanics
• Nonlinear dynamics

Background:

• Distributed fiber-optic sensing (DFOS) requires low-repetition-rate optical sources, often limited by fiber link delays.
• Existing silicon photonic optomechanical oscillators typically operate at higher frequencies or need electronic feedback.
• Purely optical, self-sustained low-frequency signal generation remains a challenge for integrated systems.

Purpose of the Study:

• To demonstrate a self-sustained silicon-photonic optomechanical oscillator operating in the low-megahertz regime.
• To develop a compact optical signal source for distributed fiber-optic sensing (DFOS) without external electronic control or radio-frequency driving.
• To investigate the nonlinear dynamical behaviors of the optomechanical oscillator.

Main Methods:

• Implementation of a silicon-on-insulator racetrack resonator with a partially suspended waveguide.
• Observation of self-sustained oscillation without radio-frequency driving or electronic feedback.
• Analysis of output waveforms in time and frequency domains, including mechanical resonance and quality factor measurement.

Main Results:

• Stable self-oscillation achieved at approximately 5.86 MHz with a near-sinusoidal waveform.
• Mechanical resonance observed with a quality factor of approximately 1100.
• Transition to nonlinear dynamical regimes with harmonic generation observed by adjusting laser cavity detuning.

Conclusions:

• Low-megahertz optomechanical oscillators are experimentally accessible on silicon photonic platforms.
• These oscillators can function as compact optical signal primitives for DFOS applications.
• The demonstrated device offers a purely optical, feedback-free approach to low-frequency signal generation.