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Updated: Jun 25, 2026
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Microwave Photonics Systems Based on Whispering-gallery-mode Resonators
Published on: August 5, 2013
Low phase-noise sapphire crystal microwave oscillators: current status.
Eugene N Ivanov1, Michael E Tobar
1School of Physics, University of Western Australia, Crawley, Australia.
Summary
Ultra-low phase-noise oscillators were developed using sapphire dielectric resonators and microwave circuit interferometry. This breakthrough achieves single-sideband phase-noise spectral density approaching -160 dBc/Hz without cryogenics.
Area of Science:
- Physics
- Electrical Engineering
- Materials Science
Background:
- Achieving ultra-low phase noise in oscillators is critical for advanced communication and sensing systems.
- Conventional methods often require cryogenic cooling or complex setups.
Purpose of the Study:
- To demonstrate the construction of ultra-low phase-noise microwave oscillators without cryogenics.
- To achieve a single-sideband phase-noise spectral density approaching -160 dBc/Hz at 1 kHz offset frequency.
Main Methods:
- Frequency locking a conventional loop oscillator to a temperature-stabilized sapphire dielectric resonator.
- Utilizing microwave circuit interferometry for the oscillator frequency control error signal.
- Employing a high microwave power level (approx. 0.5 W) in the sapphire resonator.
Main Results:
- Demonstrated ultra-low phase-noise oscillators operating at microwave frequencies (8-10 GHz).
- Achieved single-sideband phase-noise spectral density approaching -160 dBc/Hz at 1 kHz Fourier frequency.
- Successfully performed 2-oscillator phase noise measurements via microwave power variation for phase referencing.
Conclusions:
- Ultra-low phase-noise oscillators can be realized at microwave frequencies without cryogenic cooling.
- Sapphire dielectric resonators combined with microwave circuit interferometry offer a viable path to superior oscillator noise performance.
- The demonstrated technique is scalable and applicable to various high-frequency applications requiring exceptional phase stability.
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