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Q: Quantenoptik
Q 35: Laser Spectroscopy
Q 35.4: Talk
Friday, April 6, 2001, 16:30–16:45, H 2013
Absolute optical frequency metrology with a single femtosecond laser — •M. Zimmermann1, R. Holzwarth1, J. Reichert1, Th. Udem1, J.C. Knight2, W.J. Wadsworth2, P.St.J. Russel2, A. Nevsky1, M.N. Skvortsov3, S.N. Bagayev3, P. Russbüldt4, K. Gäbel4, R. Poprawe4, and T.W. Hänsch1 — 1MPI für Quantenoptik, 85748 Garching — 2Optoelectronics Group, Department of Physics, University of Bath, UK — 3Institute of Laser Physics, 630090 Novosibirsk, Russia — 4Fraunhofer Institut für Lasertechnik, Aachen
During the last two years a new method of measuring the absolute frequency of light in the IR-VIS range has been established. The new method uses the comb of modes in the frequency domain generated by the pulse train of a femtosecond (fs) laser as a ruler for measuring optical frequencies. The two degrees of freedom of the frequency comb (the repetition rate and the offset of the comb from 0 Hz) are phase coherently connected to a cesium atomic clock. The offset frequency is most conveniently accessed if the comb spans an optical octave, which can be achieved by broadening it in a photonic crystal fiber. The accuracy of the new approach has been tested on the 10−16 level [1].
As an example to demonstrate the versatility of the fs-approach we report on measurements of 16 transition frequencies of the iodine (I2) molecule around 532 nm. The potential for further simplification of the fs-approach has been demonstrated by using a directly diode pumped Cr3+LiSAF laser instead of a Ti:Sapphire laser, thus eliminating the need for an additional pump laser.
[1] R. Holzwarth et al., Phys. Rev. Lett., 85, 2264 (2000)