Long-term stability improvement of tunable optoelectronic oscillator using dynamic feedback compensation

Area of Science:

• Photonics
• Optical Engineering
• Signal Processing

Background:

• Optoelectronic oscillators (OEOs) are crucial for generating stable microwave signals.
• Long-term stability of OEOs is often limited by environmental parameter variations in fiber optic links.
• Fiber length and refractive index fluctuations, primarily due to temperature changes, introduce time delays.

Purpose of the Study:

• To propose and demonstrate a novel method for improving the long-term stability of wideband tunable OEOs.
• To mitigate the effects of fiber parameter variations on OEO performance.
• To optimize the stability of microwave signals generated by tunable OEOs.

Main Methods:

• Implemented a dynamic compensation scheme within the OEO feedback loop.
• Utilized a 900 MHz calibration signal to establish a servo system for extracting fiber link time delay.
• Employed the extracted time delay information to precisely control the tunable laser's wavelength.
• Continuously offset random delay fluctuations in the fiber link.

Main Results:

• Achieved a significant improvement in the long-term stability of the generated microwave signal.
• Demonstrated an Allan deviation improvement of more than two orders of magnitude at 2.4 GHz after 1000-s averaging time.
• Validated the effectiveness of the dynamic compensation scheme in stabilizing the OEO.

Conclusions:

• The proposed dynamic compensation method effectively enhances the long-term stability of wideband tunable OEOs.
• Precise control of laser wavelength based on real-time delay extraction is key to optimizing OEO performance.
• This technique offers a robust solution for applications requiring highly stable microwave signals.