Eur. Phys. J. D 38, 545-552 (2006)
https://doi.org/10.1140/epjd/e2006-00065-7

A rubidium-stabilized ring-cavity resonator for optical frequency metrology: precise measurement of the D₁ line in ¹³³Cs

Department of Physics, Indian Institute of Science, 560012 Bangalore, India

Corresponding author: ^a vasant@physics.iisc.ernet.in

Received: 19 October 2005
Revised: 30 December 2005
Published online: 28 March 2006

Abstract

We have developed a ring-cavity resonator that can be used to measure the absolute frequencies of optical transitions with an uncertainty below 40 kHz. The length of the resonator is calibrated against a reference laser locked to the D₂ line of ⁸⁷Rb, the frequency of which is known with 6 kHz accuracy. We demonstrate the power of this technique by measuring the absolute frequencies of various hyperfine transitions in the D₁ line of ¹³³Cs. Our results agree with earlier measurements using the frequency-comb technique, and have similar accuracy. Measurement of the D₁-line frequency could lead to a more precise determination of the fine-structure constant. We also report a precise value of A=291.918(8) MHz for the hyperfine constant in the 6P_1/2 state.