Low phase noise beams for Raman transitions with a phase modulator and a highly birefringent crystal.

We present a technique to excite Raman transitions with minimum phase noise. A phase modulator generates the Raman beams and a long calcite crystal rotates the polarization of the sidebands by 90 degrees with respect to the carrier. That polarization converts the destructive interference of the Raman pairs into constructive interference, opening the possibility to drive both co-propagating and counter-propagating transitions at high detuning with the same setup. The technique has low phase noise and a low sensitivity to vibrations or temperature fluctuations. We apply it to drive velocity insensitive Raman transitions. The crystal can be also configured to filter out one of the sidebands. (C) 2017 Optical Society of America