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Optical Frequency Measurements Group


Research in the Optical Frequency Measurements Group features two distinct but highly collaborative projects: optical frequency metrology via mode-locked fs frequency combs and optical frequency standards based on laser-cooled neutral atoms. When used in tandem, the two projects can be combined to produce optical atomic clocks, which are rapidly fulfilling their promise to become the new standard in ultra-precise timekeeping. Since participating in the first demonstration of optical clocks in 1999, while the lab was still under the direction of Dr. Leo Hollberg, we have developed comb technology for optical clock research as well as for novel applications in a variety of a other fields including: ultra-quiet microwave generation, optical waveform generation, molecular spectroscopy and fingerprinting, and calibration of astronomical spectrographs. Serving as a source of stable signals for the optical clocks, the atomic frequency references in our lab come in two flavors. The first is based on freely expanding laser-cooled Ca atoms. The second clock uses Yb atoms confined tightly in an optical lattice, which suppresses motional effects to the degree that we can construct devices with extremely high Q (> 1014), low fractional instability (σ(τ) < 3 x 10-15τ-1/2), and low uncertainty (Δf/f < 4 x 10-16). While still a developing technology, optical clocks are already outperforming other technologies in many key ways, and will enable a variety of new applications in fields such as fundamental physics, ultra-low noise electronics, and trace gas detection.

The group's research plan for the near and long term is the continued development and evaluation of the technology involved in optical frequency metrology with an emphasis on both improving the clocks and identifying (and making the clocks accessible to) important new applications.

For those interested in Chip-scale Atomic Clocks and Chip-scale Atomic Devices, please visit the Atomic Devices and Instrumentation Group website.


Publications are available though a searchable bibliography of all Time and Frequency Division publications.


    Staff contact information

    Time and Frequency Division
    Optical Frequency Measurements Group
    National Institute of Standards and Technology
    325 Broadway
    Boulder, Colorado 80305, USA
    FAX: (303) 497-7845

Last updated June 2009

What's New!

10 GHz Fs-laser

In collaboration with colleagues from Germany, scientists in the OFMG have developed a fs-laser whose higher repetition rate (10 GHz) and high power (> 1 W) should accelerate progress in a variety of applications.

For more information, see A. Bartels, D. Heinecke, and S. A. Diddams, "Passively mode-locked 10 GHz femtosecond Ti:sapphire laser", Opt. Lett. 33, 1905 (2008).