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Long-term stabilization of the length of an optical reference cavity

Gaëtan Hagel, Marie Houssin, Martina Knoop, Caroline Champenois, Michel Vedel, Fernande Vedel

physics.atom-pharXiv:physics/0507208

Abstract

To obtain a high degree of long-term length stabilisation of an optical reference cavity, its free-spectral range is locked by means of an accurate and stable frequency synthesizer. The locking scheme is twofold: a laser is locked on the Nth mode of a reference Fabry-Perot cavity and part of the laser light is shifted in frequency to be in resonance with the (N+1)th mode of the cavity. This shift is generated by an acousto-optical modulator (AOM) mounted in a double-pass scheme, matching half of the free spectral range of the reference cavity. The resulting absolute stabilization of the length of the cavity reaches the 10-11 level per second, limited by the lock transfer properties and the frequency stability of the AOM control synthesizer.

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