Abstract

The paper describes the results of the experiments on creating of a two-wavelength frequency standard on the basis of a CW frequency doubled diode-pumped Nd:YAG laser (1064nm). The narrow linewidth of the laser radiation is obtained by locking of its frequency to a high-stable zerodur Fabry-Perot interferometer by means of a phase-modulation technique. Interferometer is placed inside a vacuum chamber and thermostabilized. To obtain a high level of a long-term frequency stability, the second harmonic of the laser radiation (532nm) is locked to a saturated absorption resonance on the hyperfine structure components of the molecular-iodine X(v”=0,J”=56)→B(v’=32,J’=57) transition. Saturated absorption resonances are obtained in an external luminescent iodine cell. The length of the cell is 5cm. Molecular iodine pressure (P≈0.01Torr) in the cell is controlled by a cold finger temperature, which is thermostabilized to better than 0.1 °C. The third harmonic of the laser frequency probe modulation is used to lock laser frequency to a saturated absorption resonance. The use of a small luminescent cell and a diode-pumped Nd:YAG laser allowed to create a very compact laser system with a long-term frequency stability about 10^-13 for an averaging time of 60÷1000sec and 5×l0^-14 for a time of 200÷400sec.

© 1996 IEEE