Tests of Sapphire Crystals Manufactured With Different Growth Processes for Ultra-Stable Microwave Oscillators
Abstract
We present the characterization of 8-12 GHz whispering gallery mode resonators machined in high-quality sapphire crystals elaborated with different growth techniques. These microwave resonators are intended to constitute the reference frequency of ultra-stable Cryogenic Sapphire Oscillators. We conducted systematic tests near 4 K on these crystals to determine the unloaded Q-factor and the turnover temperature for whispering gallery modes in the 8-12 GHz frequency range. These characterizations show that high quality sapphire crystals elaborated with the Heat Exchange or the Kyropoulos growth technique are both suitable to meet a fractional frequency stability better than 1x10-15 for 1 s to 10.000 s integration times.
- Publication:
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IEEE Transactions on Microwave Theory Techniques
- Pub Date:
- January 2016
- DOI:
- 10.1109/TMTT.2015.2503748
- arXiv:
- arXiv:1504.02711
- Bibcode:
- 2016ITMTT..64...78G
- Keywords:
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- Physics - Instrumentation and Detectors
- E-Print:
- 7 figures