Cryogenic sapphire oscillator using a low- vibration design pulse-tube cryocooler: first results

Hartnett, John G.; Nand, Nitin R.; Wang, Chao; Floch, Jean-Michel Le

doi:10.1109/tuffc.2010.1515

Cited by 24 publications

(29 citation statements)

References 15 publications

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“…It was found however that there was a strong effect on the frequency stability of the oscillator at about 1000 s of averaging when run with a pressure near one atmosphere [3]. The best condition was found where the lowest pressure (about 50 kPa in practice) was allowed to develop in the helium gas space.…”

Section: Ultra-low Vibration Cryostatmentioning

confidence: 96%

“…helium cooled sapphire oscillator in the same lab [3]. In the following we show measurement of the phase noise from those same two cryogenic oscillators but using the zero beat derived with the setup shown in Fig.…”

Section: Phase Noisementioning

confidence: 99%

“…Recently a new project was started at the University of Western Australia to replicate the state-of-the-art cryogenic sapphire oscillator but using an ultra-low vibration designed cryostat [13] and a pulse tube cryo-cooler [3]. The latter paper reported only on the frequency stability when using the low vibration cryocooler and cryostat under different operating conditions.…”

mentioning

confidence: 99%

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Ultra-Low Vibration Pulse-Tube Cryocooler Stabilized Cryogenic Sapphire Oscillator With ${\hbox{10}}^{-16}$ Fractional Frequency Stability

Hartnett

Nand

2010

IEEE Trans. Microwave Theory Techn.

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Abstract-A low maintenance long-term operational cryogenic sapphire oscillator has been implemented at 11.2 GHz using an ultra-low-vibration cryostat and pulse-tube cryocooler. It is currently the world's most stable microwave oscillator employing a cryocooler. Its performance is explained in terms of temperature and frequency stability. The phase noise and the Allan deviation of frequency fluctuations have been evaluated by comparing it to an ultra-stable liquid-helium cooled cryogenic sapphire oscillator in the same laboratory. Assuming both contribute equally, the Allan deviation evaluated for the cryocooled oscillator is σy ≈ 1 × 10 −15 τ −1/2 for integration times 1 < τ < 10 s with a minimum σy = 3.9 × 10 −16 at τ = 20 s. The long term frequency drift is less than 5 × 10 −14 /day. From the measured power spectral density of phase fluctuations the single side band phase noise can be represented by L φ (f ) = 10

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Section: Ultra-low Vibration Cryostatmentioning

confidence: 96%

Section: Phase Noisementioning

confidence: 99%

mentioning

confidence: 99%

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Ultra-Low Vibration Pulse-Tube Cryocooler Stabilized Cryogenic Sapphire Oscillator With ${\hbox{10}}^{-16}$ Fractional Frequency Stability

Hartnett

Nand

2010

IEEE Trans. Microwave Theory Techn.

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“…Modes were weakly coupled via coaxial cables and loop probes so the couplings were much less than unity. The cavity was attached to the cold finger of a single stage pulse tube cryocooler 18 . Simulations were compared with these measurements for the fundamental mode 22.3 GHz.…”

Section: Measurement Setupmentioning

confidence: 99%

Cryogenic properties of a diamond sample at microwave frequencies

Floch¹,

Hartnett²,

Tobar³

et al. 2010

2010 International Conference on Electromagnetics in Advanced Applications

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International audienceDielectric resonators are key components for many microwave and millimetre wave applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. Multilayered, bulk low-loss crystal and polycrystalline dielectric structures have become very important for designing these devices. Proper design requires careful electromagnetic characterisation of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. Diamond has been recently utilized for an increasing amount of electronic applications. This paper will present the common techniques for characterizing such dielectric samples in the microwave regime, and apply it to the characterization of diamond from 35 to 330K

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“…The measurement of such CSOs is a challenging task because the target is significantly lower than the background noise of commercial instruments, and possible only by comparing three similar units. For this reason, the measurement was until now done by beating the microwave outputs, with no synthesizer [1], [2]. The use of ≈1-10 MHz beat notes relaxes the noise requirement for the instrument by 60-80 dB.…”

Section: Introductionmentioning

confidence: 99%

Frequency Stability Measurement of Cryogenic Sapphire Oscillators With a Multichannel Tracking DDS and the Two-Sample Covariance

Calosso

Vernotte

Giordano

et al. 2019

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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This article shows the first measurement of three 100 MHz signals exhibiting fluctuations from 2×10 −16 to parts in 10 −15 for integration time τ between 1 s and 1 day. Such stable signals are provided by three Cryogenic Sapphire Oscillators (CSOs) operating at about 10 GHz, also delivering the 100 MHz output via a dedicated synthesizer. The measurement is made possible by a 6-channel Tracking DDS (TDDS) and the twosample covariance tool, used to estimate the Allan variance. The use of two TDDS channels per CSO enables high rejection of the instrument background noise. The covariance outperforms the Three-Cornered Hat (TCH) method in that the background converges to zero "out of the box," with no need of the hypothesis that the instrument channels are equally noisy, nor of more sophisticated techniques to estimate the background noise of each channel. Thanks to correlation and averaging, the instrument background (AVAR) rolls off with a slope 1/ √ m, the number of measurements, down to 10 −18 at τ = 10 4 s. For consistency check, we compare the results to the traditional TCH method beating the 10 GHz outputs down to the MHz region. Given the flexibility of the TDDS, our methods find immediate application to the measurement of the 250 MHz output of the FS combs.

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Cryogenic sapphire oscillator using a low- vibration design pulse-tube cryocooler: first results

Cited by 24 publications

References 15 publications

Ultra-Low Vibration Pulse-Tube Cryocooler Stabilized Cryogenic Sapphire Oscillator With ${\hbox{10}}^{-16}$ Fractional Frequency Stability

Ultra-Low Vibration Pulse-Tube Cryocooler Stabilized Cryogenic Sapphire Oscillator With ${\hbox{10}}^{-16}$ Fractional Frequency Stability

Cryogenic properties of a diamond sample at microwave frequencies

Frequency Stability Measurement of Cryogenic Sapphire Oscillators With a Multichannel Tracking DDS and the Two-Sample Covariance

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