title: Coherent multiwave heterodyne frequency measurement of a far-infared laser by means of a femtosecond laser comb.
abstract: We demonstrate the possibility of using a femtosecond laser to measure with high accuracy the frequency of a far-infrared (FIR) monochromatic source, such as an optically pumped molecular laser, by generating in a suitable mixer a signal in the radio-frequency region at the frequency difference between n steps of a femtosecond comb and the FIR source. All the couples of modes lying a distance of n steps from one another contribute coherently to the heterodyne signal. The technique has been tested up to 670 GHz.
authors.affiliation: Dipartimento di Fisica Enrico Fermi dell'Università di Pisa and Istituto Nazionale per la Fisica della Materia, Via F. Buonarroti 2, 56127 Pisa, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Beverini
authors.forename: G
authors.initials: G
authors.lastname: Carelli
authors.forename: A
authors.initials: A
authors.lastname: De Michele
authors.forename: E
authors.initials: E
authors.lastname: Maccioni
authors.forename: B
authors.initials: B
authors.lastname: Nyushkov
authors.forename: F
authors.initials: F
authors.lastname: Sorrentino
authors.forename: A
authors.initials: A
authors.lastname: Moretti