title: Demonstration of a HeNe/CH4-based optical molecular clock.
abstract: We implement a simple optical clock based on the F2(2) [P(7), v3] optical transition in methane. A single femtosecond laser's frequency comb undergoes difference frequency generation to provide an IR comb at 3.39 microm with a null carrier-envelope offset. This IR comb provides a phase-coherent link between the 88-THz optical reference and the rf repetition rate. Comparison of the repetition rate signal with a second femtosecond comb stabilized to molecular iodine shows an instability of 1.2 x 10(-13) at 1 s, limited by microwave detection of the repetition rates. The single-sideband phase noise of the microwave signal, normalized to a carrier frequency of 1 GHz, is below -93 dBc/Hz at 1-Hz offset.
authors.affiliation: JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA. foreman@colorado.edu
authors.forename: Seth M
authors.initials: SM
authors.lastname: Foreman
authors.forename: Adela
authors.initials: A
authors.lastname: Marian
authors.forename: Jun
authors.initials: J
authors.lastname: Ye
authors.forename: Evgeny A
authors.initials: EA
authors.lastname: Petrukhin
authors.forename: Mikhail A
authors.initials: MA
authors.lastname: Gubin
authors.forename: Oliver D
authors.initials: OD
authors.lastname: Mücke
authors.forename: Franco N C
authors.initials: FN
authors.lastname: Wong
authors.forename: Erich P
authors.initials: EP
authors.lastname: Ippen
authors.forename: Franz X
authors.initials: FX
authors.lastname: Kärtner