Optical Clockworks with Femtosecond Lasers

Femtosecond-laser-based optical clockwork

Emerging optical frequency standards based on laser-cooled atoms and ions promise superior stability and accuracy over existing microwave standards. However, until recently an appropriate clockwork for dividing down the very fast optical oscillations to a countable frequency had been missing. As demonstrated in just the past year, frequency dividers based on mode-locked femtosecond lasers and microstructure optical fiber provide a convenient, robust, and accurate means of phase-coherently linking optical frequencies to standards in the microwave domain. This breakthrough has revolutionized optical frequency metrology and opened the door to a new generation of atomic clocks based on optical transitions.

Scott Diddams, NIST, sdiddams@boulder.nist.gov

References:

S. A. Diddams, D. J. Jones, Jun Ye, T.M. Fortier, R.S. Windeler, S. T. Cundiff, T. W. Hänsch, and J. L. Hall "Toward the ultimate control of light: Optical frequency metrology and the phase control of femtosecond pulses," Optics & Photonics News 11, 16 (2000).

K. R. Vogel, S. A. Diddams, C. W. Oates, E. A. Curtis, R. J. Rafac, W. M. Itano, J. C. Bergquist, R. W. Fox, W. D. Lee, J. S. Wells and L. Hollberg, "Direct comparison between two cold-atom-based optical frequency standards using a femtosecond-laser comb," Opt. Lett. 26, 102 (2001).

S. A. Diddams, Th. Udem, K. R. Vogel, C. W. Oates, E. A. Curtis, R. S. Windeler, A. Bartels, J. C. Bergquist, and L. Hollberg,
"A compact femtosecond-laser-based optical clockwork," in Laser Frequency Stabilization, Standards, Measurement, and Applications, J. L. Hall, J. Ye, eds., Proceedings of SPIE, vol. 4269, pp. 77-83 (2001).

Th. Udem, S. A. Diddams, K. R. Vogel, C. W. Oates, E. A. Curtis, W. D. Lee, W. M. Itano, R.E. Drullinger, J. C. Bergquist, and L. Hollberg, "Absolute frequency measurements of the Hg⁺ and Ca optical clock transitions with a femtosecond laser," Phys. Rev. Lett. 86, 4996 (2001).

S. A. Diddams, Th. Udem, J. C. Bergquist, E. A. Curtis, R. E. Drullinger, L. Hollberg, W. M. Itano, W. D. Lee, C. W. Oates, K. R. Vogel, and D. J. Wineland, "An optical clock based on a single trapped¹⁹⁹Hg⁺ ion," Science 293, 825 (2001).

L. Hollberg, C. W. Oates, E. A.Curtis, E. N. Ivanov, S. A. Diddams, Th.Udem, H. G. Robinson, J. C. Bergquist, R. J. Rafac, W. M. Itano, R. E. Drullinger, and D. J. Wineland, "Optical frequency standards and measurements," IEEE J. Quant. Electon. 37, 1502 (2001).

S. A. Diddams, L. Hollberg, L.-S. Ma, and L. Robertsson, “Femtosecond-laser-based optical clockwork with instability < 6.3 X 10^-16 in 1 s”, Opt. Lett. 27, 58 (2002).

T. M. Ramond, S. A. Diddams. L. Hollberg, A. Bartels, "Phase coherent link from optical to microwave frequencies via the broadband continuum from a 1 GHz Ti:sapphire femtosecond oscillator", Opt. Lett. 27, 20 (2002).

Acknowledgements

This work has benefited greatly from collaborations with Thomas Udem (Max Plank Institute for Quantum Optics), Robert Windeler (Lucent Technologies) and Albrecht Bartels (GigaOptics).