Phase noise performance comparison between optoelectronic oscillators based on optical delay lines and whispering...

Area of Science:

• Photonics
• Microwave Engineering
• Resonator Technology

Background:

• Optoelectronic oscillators (OEOs) are crucial for high-frequency signal generation.
• Phase noise performance is a key metric for OEOs, impacting signal integrity.
• Optical energy storage elements, like resonators and delay-lines, influence OEO stability and spectral purity.

Purpose of the Study:

• To investigate and compare the phase noise performance of OEOs with different optical energy storage configurations.
• To characterize the stability properties of whispering gallery mode resonators and optical delay-lines.
• To analyze the spectral purity of OEOs using theoretical and experimental methods for each configuration.

Main Methods:

• Characterization of stability properties for high-Q whispering gallery mode resonators and optical delay-lines.
• Systematic comparison of optical and microwave frequency domain characteristics.
• Theoretical and experimental examination of spectral purity in OEOs for three configurations: resonator-only, delay-line-only, and combined resonator-delay-line.
• Measurement of spurious mode rejection.

Main Results:

• The stability properties of individual optical elements were characterized.
• Spectral purity was theoretically and experimentally examined for all configurations.
• Using a resonator as both a delay and filtering element in a delay-line based OEO demonstrated high spurious mode rejection.
• A spur rejection exceeding 53 dB was achieved for the first-neighboring spur.

Conclusions:

• The combination of a whispering gallery mode resonator and an optical delay-line offers superior phase noise performance in OEOs.
• Resonator-based filtering within a delay-line OEO is effective in suppressing spurious modes.
• This approach provides a viable method for achieving high spectral purity in OEOs.