Low-noise dual-frequency laser for compact Cs atomic clocks

Paul Dumont (1) , Fabiola Camargo (1) , Jean-Marie Danet (2) , David Holleville (2) , Stéphane Guerandel (2) , Grégoire Pillet (3) , Ghaya Baili (3) , Loïc Morvan (3) , Daniel Dolfi (3) , Iryna Gozhyk (4, 1) , Grégoire Beaudoin (4) , Isabelle Sagnes (4) , Patrick Georges (1) , Gaëlle Lucas-Leclin (1)

1 Laboratoire Charles Fabry / Lasers
2 LNE - SYRTE - Laboratoire national de métrologie et d'essais - Systèmes de Référence Temps-Espace
3 Thales Research and Technology [Palaiseau]
4 LPN - Laboratoire de photonique et de nanostructures

We report the dual-frequency and dual-polarization emission of an optically-pumped vertical external-cavity semiconductor laser (OP-VECSEL). Our laser source provides a high-purity optically-carried RF signal tunable in the GHz range, and is specifically designed for the coherent population trapping (CPT) of Cs atoms in compact atomic clocks. The laser spectrum is stabilized onto a Cs atomic transition at 852.1 nm, and the frequency difference is locked to a local oscillator at 9.2 GHz. Special attention has been paid to the evaluation of the frequency, intensity and phase noise properties. A maximum phase noise of - 90 dBrad2/Hz has been measured. Finally, we estimate the contribution of the laser noise on the short-term frequency stability of a CPT atomic clock, and predict that a value below 3 × 10-13 over one second is a realistic target.

Keywords: Vertical cavity surface emitting lasers; Microwave photonics; Laser noise; Clocks; Laser noise.

Domains: Optics [physics.optics]

Paul Dumont, Fabiola Camargo, Jean-Marie Danet, David Holleville, Stéphane Guerandel, et al.. Low-noise dual-frequency laser for compact Cs atomic clocks. Journal of Lightwave Technology, 2014, 32 (20), pp.3817-3823. ⟨10.1109/JLT.2014.2318179⟩. ⟨hal-01060557⟩