A frequency comparison was carried out between iodine-stabilized Nd:YAG lasers at 532 nm from the Bureau International des Poids et Mesures, the Centre for Metrology and Accreditation, the Czech Metrology Institute, and the Bureau National de Métrologie-Institut National de Métrologie. The frequency differences between lasers, as well as the frequency reproducibility of each system, were investigated. Pressure-, modulation-, and power-induced shifts were studied. A frequency dispersion (1 ς) of 3.5 kHz (6.2 × 10<sup>−12</sup> in relative terms) with an average reproducibility for each laser of the order of 0.4 kHz (7.1 × 10<sup>−13</sup> in relative terms) was observed over the duration of the comparison. Relative stabilities better than 1 × 10<sup>−13</sup> at 1 s were demonstrated for the third-harmonic systems.
© 2003 Optical Society of America
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(140.3500) Lasers and laser optics : Lasers, erbium
(300.1030) Spectroscopy : Absorption
(300.6460) Spectroscopy : Spectroscopy, saturation
Susanne Picard, Lennart Robertsson, Long-Sheng Ma, Kaj Nyholm, Mikko Merimaa, Tero E. Ahola, Petr Balling, Petr Kr˘en, and Jean-Pierre Wallerand, "Comparison of 127I2-Stabilized Frequency-Doubled Nd:YAG Lasers at the Bureau International des Poids et Mesures," Appl. Opt. 42, 1019-1028 (2003)