Amplitude noise and linewidth reduction of an Ar/sup +/ laser

Frequency modulation spectroscopy is used to frequency stabilize an Ar/sup +/ laser at 515 nm with respect to a commercial passive cavity. Two transducers, a slow and a fast one, are used. The fast transducer is also used to perform amplitude stabilization of a laser beam. Measured amplitude and frequency spectral noise densities are reported. A simplified scheme of the circuitry used to reduce amplitude noise is shown. Noise characteristics of the realized system are adequate to perform spectroscopy of hyperfine-structure transitions of molecular iodine.