Femtosecond-laser frequency combs revolutionized the field of precision metrology after their introduction in 1999. Today, they are commonly used in atomic clock calibration, low-noise frequency synthesis, astronomical spectrograph calibration and precision spectroscopy. Scientists are now pushing to extend frequency combs into the mid-infrared and extreme ultraviolet spectral region with Yb:fiber technology.
© 2012 Optical Society of America
Axel Ruehl, "Advances in Yb:Fiber Frequency Comb Technology," Optics & Photonics News 23(5), 30-35 (2012)