ACCURATE OPTICAL FREQUENCY-INTERVAL MEASUREMENT BY USE OF NONRESONANTFREQUENCY COMB GENERATION

A novel technique for measuring the separation of widely spaced optica l frequencies is demonstrated. It relies on frequency comb generation by use of a laser that incorporates a frequency-shifting element. A Nd :YLF laser is used to produce a frequency comb that has a bandwidth of 140 GHz and that contains in excess of 875 discrete frequencies, accu rately spaced by 160 MHz. The longitudinal mode spacing of a dual-freq uency laser was measured to an accuracy of +/- 5 kHz in 3,733,440.0 kH z by use of the technique described here.