Phase shift in an atom interferometer induced by the additional laser lines of a Raman laser generated by modulation

The use of a Raman laser generated by modulation for a light-pulse atom interferometer allows for a laser system that is compact and robust. However, the additional laser frequencies generated can perturb the atom interferometer. In this article, we present a precise calculation of the phase shift induced by the additional laser frequencies. The model is validated by comparison with experimental measurements on an atom gravimeter. The uncertainty of the phase-shift determination limits the accuracy of our compact gravimeter to 8×10^-80.28em0exm/s². We show that it is possible to reduce this inaccuracy considerably with a better control of experimental parameters or with particular interferometer configurations.