An optical clockwork is created with a compact 1-GHz repetition-rate laser and three nonlinear crystals. The broadband continuum output of the laser covers sufficient bandwidth to provide direct access to its carrier-envelope offset frequency without the use of a microstructure fiber. We phase lock the femtosecond comb to a Ca optical standard and monitor the stability of the repetition rate, ƒ<sub>r</sub> , at 1 GHz. We demonstrate that the short-term stability of the microwave output of the optical clock is at least as good as that of a high-performance hydrogen maser.
© 2002 Optical Society of America
(120.3940) Instrumentation, measurement, and metrology : Metrology
(140.4050) Lasers and laser optics : Mode-locked lasers
(190.2620) Nonlinear optics : Harmonic generation and mixing
(320.7090) Ultrafast optics : Ultrafast lasers
T. M. Ramond, S. A. Diddams, L. Hollberg, and A. Bartels, "Phase-coherent link from optical to microwave frequencies by means of the broadband continuum from a 1-GHz Ti:sapphire femtosecondoscillator," Opt. Lett. 27, 1842-1844 (2002)