Laser frequency locking with 46 GHz offset using an electro-optic   modulator for magneto-optical trapping of francium atoms
  We demonstrated a frequency offset locking between two laser sources using a waveguide-type electro-optic modulator (EOM) with 10th-order sidebands for magneto-optical trapping of Fr atoms. The frequency locking error signal was successfully obtained by performing delayed self-homodyne detection of the beat signal between the repumping frequency and the 10th-order sideband component of the trapping light. Sweeping the trapping-light and repumping-light frequencies with keeping its frequency difference of 46 GHz was confirmed over 1 GHz by monitoring the Doppler absorption profile of I2. This technique enables us to search for a resonance frequency of magneto-optical trapping of Fr. 
K. Harada, T. Aoki, S. Ezure, K. Kato, T. Hayamizu, H. Kawamura, T.   Inoue, H. Arikawa, T. Ishikawa, T. Aoki, A. Uchiyama, ...
physics.atom-ph