Frequency comparison and absolute frequency measurement of I sub(2)-stabilized lasers at 532 nm

A frequency comparison and an absolute frequency measurement of iodine stabilized frequency-doubled Nd:YAG lasers at 532 nm has been performed at the Max-Planck-Institute for Quantum Optics. Two independent I sub(2 )-stabilized laser systems, one assembled at the Institute of Laser Physics, Novosibirsk, Russia, the other at the Physikalisch-Technische Bundesanstalt, Braunschweig, Germany were investigated. Using a phase-coherent frequency chain, the absolute frequency of the I sub(2)-stabilized lasers has been compared to a CH sub(4)-stabilized He-Ne laser at 3.39 mu m which has been calibrated against an atomic cesium fountain clock. A new value for the R(56)32-0:a sub(10) component, recommended by the Comite International des Poids et Mesures for the realization of the meter [Metrologia 30 (1993/1994) 523; Metrologia 36 (1999) 211], has been obtained with reduced uncertainty. Improved absolute frequency values of the R(56)32-0 and P(54)32-0 iodine absorption lines together with the hyperfine line separations are presented. copyright 2001 Elsevier Science B.V.