Investigation of techniques for absolute laser frequency measurements using an optical femtosecond comb generator

Final report, 15 October 2004

During the cooperation absolute laser frequencies of three type of lasers have been determined. The main outcome was the proof that the comb generator can be used to calibrate the type of lasers commonly used in length metrology (with low output power and/or strong frequency modulation). Depending on the respective wavelength output powers as low as 10 µW are measurable.

As a side product the absolute frequencies of following iodine stabilized lasers were determined:

532nm, Frequency doubled Nd:YAG-laser CMI YAG1
32-0 R(56) a10       563 260 223 514.3 kHz (0.4 kHz)
543nm, green HeNe-Laser PLG1
28-0 R(106) b10       551 580 162 396.6 kHz (0.6 kHz)
633nm, red HeNe-Laser BEV2
11-5 R(127) f       473 612 353 604.36 kHz (0.14 kHz)


Since there was no interest for the calibration of lasers with other wavelengths, the project is now finished.


This project is dedicated to the evaluation of the optical femtosecond comb generator which was set up at the BEV in the beginning of 2002. The main interest of this research is to optimize the methods for getting a good beat signal with the low power stabilized lasers sources commonly used in NMI’s for the realization of the unit of length. First measurements on the iodine stabilized lasers BEV1 and BEV2 (??˜ 633 nm) with an output power of approximately 100 µW were already successful.

To investigate this systems at other wavelengths, measurements with different laser sources are essential. The CMI has a long experience on iodine stabilized lasers other than 633 nm (543 nm, 612 nm, [HeNe] and 532 nm, 1064 nm [Nd:YAG]). Theirs laser are well characterized in international comparisons and are easily transportable.

Length (L)
Coordinating Institute
BEV (Austria)
Participating Partners
CMI (Czech Republic)