DIODE-LASER SPECTROSCOPY IN A CA ATOMIC-BEAM

The frequency of an extended cavity diode laser has been stabilized to a resonance of a high-Q optical resonator by using the rf phase modulation technique. A servo bandwidth of 200 kHz has been achieved using a two channel control loop with the fast corrections applied to the injection current and the slow ones to a piezo-driven external cavity mirror of the laser. The laser has been utilized for separated field excitation of the S-1(0)-P-3(1) intercombination line (lambda congruent-to 657 nm) in a Ca atomic beam. We have observed optical Ramsey resonances, with the recoil splitting of 23.1 kHz being resolved and the spectral line widths have been as small as 10 kHz.