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

A frequency comparison and an absolute frequency measurement of iodine stab ilized frequency-doubled Nd:YAG lasers at 532 nm has been performed at the Max-Planck-Institute for Quantum Optics. Two independent I-2-stabilized las er systems, one assembled at the Institute of Laser Physics, Novosibirsk, R ussia, the other at the Physikalisch-Technische Bundesanstalt, Braunschweig , Germany were investigated. Using a phase-coherent frequency chain, the ab solute frequency of the I-2-stabilized lasers has been compared to a CH4-st abilized He-Ne laser at 3.39 mum which has been calibrated against an atomi c cesium fountain clock. A new value for the R(56)32-0:a(10) component, rec ommended by the Comite International des Poids et Mesures for the realizati on of the meter [Metrologia 30 (1993/1994) 523; Metrologia 36 (1999) 211], has been obtained with reduced uncertainty. Improved absolute frequency val ues of the R(56)32-0 and P(54)32-0 iodine absorption lines together with th e hyperfine line separations are presented. (C) 2001 Elsevier Science B.V. All rights reserved.