Wideband tunable opto-electronic oscillator based on frequency translation

Area of Science:

• Electrical Engineering
• Physics
• Signal Processing

Background:

• Opto-electronic oscillators (OEOs) are crucial for high-frequency signal generation.
• Achieving wide tunability while maintaining low phase noise in OEOs is a significant challenge.
• Existing methods often involve trade-offs between tunability and phase noise performance.

Purpose of the Study:

• To demonstrate a new method for creating a widely tunable, low phase-noise opto-electronic oscillator (OEO).
• To enable precise frequency control of OEOs using a tunable local oscillator (LO) without compromising phase noise.
• To enhance the effective Q-factor of the OEO's filtering mechanism.

Main Methods:

• The proposed method involves downconverting the OEO signal to a lower intermediate frequency (IF) using a local oscillator (LO).
• A high-Q filter is applied at the IF, followed by upconversion back to the original OEO frequency.
• A tunable LO combined with a fixed-frequency, narrowband filter creates a tunable high-Q bandpass filter (BPF).

Main Results:

• A widely tunable low phase-noise OEO was successfully demonstrated.
• The dual frequency conversion effectively suppressed the phase noise introduced by the LO.
• The system allowed for broad frequency tuning of the OEO by adjusting the LO frequency.

Conclusions:

• The developed method provides a robust solution for achieving wide tunability in low phase-noise OEOs.
• This technique allows the use of a tunable LO with potentially higher phase noise to control a very low phase-noise OEO.
• The approach enhances the effective Q-factor, leading to improved oscillator performance.