title: Direct link between microwave and optical frequencies with a 300 THz femtosecond laser comb
abstract: We demonstrate a great simplification in the long-standing problem of measuring optical frequencies in terms of the cesium primary standard. An air-silica microstructure optical fiber broadens the frequency comb of a femtosecond laser to span the optical octave from 1064 to 532 nm, enabling us to measure the 282 THz frequency of an iodine-stabilized Nd:YAG laser directly in terms of the microwave frequency that controls the comb spacing. Additional measurements of established optical frequencies at 633 and 778 nm using the same femtosecond comb confirm the accepted uncertainties for these standards.
authors.affiliation: JILA, University of Colorado, and National Institute of Standards and Technology, Boulder, Colorado 80309, USA.
authors.initials: SA
authors.lastname: Diddams
authors.initials: DJ
authors.lastname: Jones
authors.initials: J
authors.lastname: Ye
authors.initials: ST
authors.lastname: Cundiff
authors.initials: JL
authors.lastname: Hall
authors.initials: JK
authors.lastname: Ranka
authors.initials: RS
authors.lastname: Windeler
authors.initials: R
authors.lastname: Holzwarth
authors.initials: T
authors.lastname: Udem
authors.initials: TW
authors.lastname: Hansch