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Xiaopeng Xie 1‡, Romain Bouchand 1‡, Daniele Nicolodi 1†, Michele Giunta 2,3, Wolfgang Hänsel 2, Matthias Lezius 2, Abhay Joshi 4, Shubhashish Datta 4, Christophe Alexandre 5, Michel Lours 1, Pierre-Alain Tremblin 6, Giorgio Santarelli 6, Ronald Holzwarth 2,3, and Yann Le Coq 1
1 LNE-SYRTE, Observatoire de Paris, CNRS, UPMC, 61 avenue de I'Observatoire, Cedex 75014 Paris, France.
2 Menlo Systems GmbH, Am Klopferspitz 19a, D-82152 Martinsried, Germany.
3 Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
4 Discovery Semiconductors Inc., 119 Silvia Street, Ewing, New Jersey 08628, USA.
5 CNAM, CEDRIC Laboratory, 292 rue Saint Martin,Cedex 75003 Paris, France.
6 LP2N, IOGS – CNRS – Université de Bordeaux 1, rue F. Mitterand,Cedex 33400 Talence, France.
† Present address: National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
‡ These authors contributed equally to this work.ABSTRACT
Photonic synthesis of radiofrequency (RF) revived the quest for unrivalled microwave purity by its seducing ability to convey the benefits of optics to the microwave world. In this work, we perform a high-fidelity transfer of frequency stability between an optical reference and a microwave signal via a low-noise fiber-based frequency comb and cutting-edge photodetection techniques. We demonstrate the generation of the purest microwave signal with a fractional frequency stability below 6.5×10-16 at one second and a timing noise floor below 41 zs Hz -1/2 (phase noise below −173 dBc Hz-1 for a 12 GHz carrier). This outclasses existing sources and promises a new era for state-of-the-art microwave generation. The characterization is achieved through a heterodyne cross-correlation scheme with the lowermost detection noise. This unprecedented level of purity can impact domains such as radar systems, telecommunications and time–frequency metrology. The measurement methods developed here can benefit the characterization of a broad range of signals.
* Nature Photonics, Volume 11, pp. 44-47, 2017
Related links: Photonic microwave signals with zeptosecond-level absolute timing noise
