Jeudi 4 octobre 2001
Femtosecond laser frequency comb techniques are vastly simplifying the measaurement and synthesis of optical frequencies. A single mode-locked femtosecond laser can produce millions of sharp laser lines in a precisely evely spaced grid spanning much of the visible and near-infrared spectrum. The absolute frequency of each line is determined by two observable radiofrequency signals.
Such optical frequency comb synthesizers have already been used to measure optical frequencies of sharp transitions in atoms, ions, or molecules with unprecedented precision. They provide an ultraprecise „clockwork" for future atomic clocks based on optical transitions, and they will enablenew tests of special and general relativity, or new laboratory searches for possible slow variations of fundamental constants.