Line-center stabilized CO2lasers as secondary frequency standards: Determination of pressure shifts and other errors

Author

Soohoo, Kie L. ; Freed, Charles ; Thomas, John E. ; Haus, Hermann A.

Author_Institution

Rockwell International, Anaheim, CA, USA

Volume

21

Issue

8

fYear

1985

fDate

8/1/1985 12:00:00 AM

Firstpage

1159

Lastpage

1171

Abstract

The 4.3 μm CO2fluorescence stabilization method is reviewed and a two-channel heterodyne system with a fractional frequency stability of $\\sigma _{y}(\\tau ) < 2 \\times 10^{-12}$ is described. Frequency reproducibility and causes of frequency shifts and errors in the saturation resonance are discussed. A new technique is employed to eliminate frequency offset errors caused by the nonzero slope of the power versus frequency characteristics of the lasers over the frequency range of the nonlinear resonance dip. Pressure shifts of the standing wave saturated resonance have been measured in the 9 and 10 μm $P$ and $R$ lasing transitions of CO2. At low pressures (≤ 100 mTorr) the measured shifts for four different isotopes are all blue, instead of red as predicted by semiclassical theory. Measurements at higher (> 1 Torr) pressures reveal red shifts. Perturber gas data show blue shifts for heavier perturber atoms or molecules, red shifts for He and H2.

Keywords

Carbon dioxide lasers; Frequency measurement; Laser stability; Measurement standards; Atomic measurements; Fluorescence; Frequency; Isotopes; Laser transitions; Power lasers; Pressure measurement; Reproducibility of results; Resonance; Stability;

fLanguage

English

Journal_Title

Quantum Electronics, IEEE Journal of

Publisher

ieee

ISSN

0018-9197

Type

jour

DOI

10.1109/JQE.1985.1072806

Filename

1072806