Short and long term stability of optical oscillators

Progress in making stable laser sources which can be used as local oscillators for an optical atomic frequency standard is reported. For short-term stability, the laser frequency was stabilized to the resonance frequency of a high-finesse Fabry-Perot cavity. Linewidths of 50 mHz (FWHM) for He-Ne lasers and 0.49 Hz (FWHM) for a commercial dye laser system were obtained. By locking the optical phase of a commercial dye laser system to a reference laser, more than 97% of the power could be put into the carrier, which means >97% of the dye laser power is within the linewidth of the reference laser. With both passive and active vibration isolation of the optical table on which the reference cavities are mounted, <1-μg seismic vibration and <1-μrad tilt environment, corresponding to <20-Hz laser frequency excursion and <10-Hz frequency shift, respectively, were obtained. The long term drift was also studied