The Parametric Frequency-Interval Divider

Abstract

During the last twenty years, two techniques have been developed to measure the frequency of visible radiation with respect to a Cs primary clock: harmonic frequency chains [1], and frequency chains operating in the difference frequency domain [2]. The latter technique has turned out to be much more flexible, since its spectral coverage can be restricted to the near-infrared and visible range, where tunable light sources are readily available. In particular, with the advent of optical frequency-comb generators based on Kerr-lens mode-locked lasers [3] this technique permits the measurement of any unknown frequency in this spectral range.