Double-heterodyne probing for ultra-stable laser based on spectral hole burning in a rare-earth doped crystal

N. Galland (1, 2) , N Lučić (2) , S Zhang (2) , H Alvarez-Martinez (2, 3) , R Le Targat (2) , A Ferrier (4, 5) , P Goldner (4) , B Fang (2) , S. Seidelin (1, 6) , Y Le Coq (2)

1 NEEL - NOF - Nano-Optique et Forces
2 LNE - SYRTE - Laboratoire national de métrologie et d'essais - Systèmes de Référence Temps-Espace
3 ROA - Real Instituto y Observatorio de la Armada
4 IRCP - Institut de Recherche de Chimie Paris
5 SU - Sorbonne Université
6 IUF - Institut universitaire de France

We present an experimental technique for realizing a specific absorption spectral pattern in a rare-earth-doped crystal at cryogenic temperatures. This pattern is subsequently probed on two spectral channels simultaneously, thereby producing an error signal allowing frequency locking of a laser on the said spectral pattern. Appropriate combination of the two channels leads to a substantial reduction of the detection noise, paving the way to realizing an ultra-stable laser for which the detection noise can be made arbitrarily low when using multiple channels. We use such technique to realize a laser with a frequency instability of $\mathbf{1.7\times10^{-15}}$ at 1 second, not limited by the detection noise but by environmental perturbation of the crystal. This is comparable with the lowest instability demonstrated at 1 second to date for rare-earth doped crystal stabilized lasers.

Domaines: Optique [physics.optics]

N. Galland, N Lučić, S Zhang, H Alvarez-Martinez, R Le Targat, et al.. Double-heterodyne probing for ultra-stable laser based on spectral hole burning in a rare-earth doped crystal. Optics Letters, 2020, 45 (7), pp.1930-1933. ⟨10.1364/OL.389833⟩. ⟨hal-02527623⟩