The Autonomous Cryocooled Sapphire Oscillator: A Reference for Frequency Stability and Phase Noise Measurements

8th Symposium on Frequency Standards and Metrology 2015

Giordano, V.^1 ; Grop, S.^2 ; Fluhr, C.^1 ; Dubois, B.^3 ; Kersalé, Y.^1 ; Rubiola, E.^1

Dept TF, FEMTO-ST Institute, CNRS UMR 6174, Besançon, France^1

Alemnis GmbH, Feuerwerkerstrasse 39, Thun

3602, Switzerland^2

FEMTO Engineering, 32 avenue de l'Observatoire, Besançon

25000, France^3

关键词: Cryogenic sapphire oscillators;    Measurement methods;    Microwave Photonics;    Phase noise measurement;    Pulse tube cryocoolers;    Sapphire oscillators;    Short term stability;    Traveling standards;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/723/1/012030/pdf
DOI  :  10.1088/1742-6596/723/1/012030

来源: IOP

【 摘 要 】

The Cryogenic Sapphire Oscillator (CSO) is the microwave oscillator which feature the highest short-term stability. Our best units exhibit Allan deviation σy(τ) of 4.5×10-16at 1s, ≈ 1.5×10-16at 100 s ≤ t ≤ 5,000 s (floor), and ≤ 5x10-15at one day. The use of a Pulse-Tube cryocooler enables full two year operation with virtually no maintenance. Starting with a short history of the CSO in our lab, we go through the architecture and we provide more details about the resonator, the cryostat, the oscillator loop, and the servo electronics. We implemented three similar oscillators, which enable the evaluation of each with the three- cornered hat method, and provide the potential for Allan deviation measurements at parts of 10-17level. One of our CSOs (ULISS) is transportable, and goes with a small customized truck. The unique feature of ULISS is that its σy(τ) can be validated at destination by measuring before and after the roundtrip. To this extent, ULISS can be regarded as a traveling standard of frequency stability. The CSOs are a part of the Oscillator IMP project, a platform dedicated to the measurement of noise and short-term stability of oscillators and devices in the whole radio spectrum (from MHz to THz), including microwave photonics. The scope spans from routine measurements to the research on new oscillators, components, and measurement methods.