Phase-coherent frequency measurement of the Ca intercombination line at 657 nm with a Kerr-lens mode-locked femtosecond laser - art. no. 021802

摘要

The frequency of the calcium P-3(1)-S-1(0) intercombination line at 657 nm is phase-coherently measured in terms of the output of a primary cesium frequency standard using an optical frequency comb generator comprising a sub-10-fs Kerr-lens mode-locked Ti:sapphire laser and an external microstructure fiber for self-phase-modulation. The measured frequency of nu (Ca) = 455 986 240 494 276 Hz agrees within its relative uncertainty of 4 x 10(-13) with the values previously measured with a conceptually different harmonic frequency chain and with the value recommended for the realization of the SI unit of length. [References: 20]