Details

Autor(en) / Beteiligte

• Hartnett, John G
• Nand, Nitin R

Titel

Ultra-Low Vibration Pulse-Tube Cryocooler Stabilized Cryogenic Sapphire Oscillator With }^ Fractional Frequency Stability

Ist Teil von

• IEEE transactions on microwave theory and techniques, 2010-12, Vol.58 (12), p.3580-3586

Ort / Verlag

New York: IEEE

Erscheinungsjahr

2010

Link zum Volltext

• IEEE_Xplore

Quelle

IEL

Beschreibungen/Notizen

• 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 σ y ≈ 1 × 10 -15 τ -1/2 for integration times 1 <; τ <; 10 s with a minimum σ y = 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-sideband phase noise can be represented by L φ ( f ) = 10 -14.0 / f 4 +10 -11.6 / f 3 +10 -10.0 / f 2 +10 -10.2 / f + 10 -11.0 rad 2 /Hz for Fourier frequencies 10 -3 <; f <; 10 3 Hz in the single oscillator. As a result, L φ ≈ -97.5 dBc/Hz at 1-Hz offset from the carrier.