[1] Univ Paris 06, Sorbonne Univ, LERMA, UMR 8112, F-75005 Paris, France
[2] PSL Res Univ, CNRS, Observ Paris, LERMA,UMR 8112, F-75014 Paris, France
[3] Grad Sch, Inst Opt, F-91127 Palaiseau, France
[4] UPMC, CNRS, Observ Paris, LNE SYRTE, F-75014 Paris, France
[5] NIST, Boulder, CO 80305 USA
[6] Univ Pisa, Dipartimento Fis E Fermi, I-56122 Pisa, Italy