Abstract

So far, the use of optical frequency standards for the realization of basic units, e.g. of time and length, was hampered by the difficulties of measuring their high frequencies. Recent progress in femtosecond pulse generation and the advent of microstructure optical fibers, however, have substantially facilitated such optical frequency measurements. These schemes¹⁻⁴ start with the highly periodic pulse train of a Kerr-lens mode- locked laser which corresponds in the frequency domain to a comb-like frequency spectrum of equidistant lines.

© 2001 Optical Society of America