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A cryogenic open-cavity sapphire reference oscillator with low spurious mode density
Pierre-Yves Bourgeois1, Yann Kersalé, Nicolas Bazin
1Departement Laboratoire de Physique et de Métrologie des Oscillateurs, Institut FEMTO-ST Unité Mixte de Recherche UMR 6174, F-25044 Besançon, France.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
|November 24, 2004
Summary
We developed a microwave cryogenic sapphire oscillator (CSO) achieving excellent short-term frequency stability. This CSO offers a new reference for characterizing signal sources with high precision.
Area of Science:
- Physics
- Metrology
- Electrical Engineering
Background:
- Cryogenic sapphire oscillators (CSOs) are crucial for high-precision frequency standards.
- Spurious modes in sapphire resonators can degrade oscillator performance.
Purpose of the Study:
- To implement a microwave CSO at the Laboratoire de Physique et Métrologie des Oscillateurs.
- To address and overcome challenges related to spurious modes in sapphire resonators.
- To evaluate the frequency stability of the implemented CSO and explore its application as a reference oscillator.
Main Methods:
- Operating the sapphire resonator in an open cavity configuration to mitigate spurious modes.
- Comparing the CSO's performance against a hydrogen maser.
- Utilizing the CSO for characterizing other signal sources.
Main Results:
- Successful implementation of a microwave CSO.
- Frequency stability better than 3 x 10⁻¹⁴ at short term achieved.
- Long-term frequency instability measured at approximately 3 x 10⁻¹² per day, limited by a random walk process.
Conclusions:
- The open cavity design effectively suppressed spurious modes in the sapphire resonator.
- The CSO demonstrates superior short-term frequency stability compared to traditional standards.
- The CSO shows potential as a high-performance reference oscillator for signal source characterization.