[2] Evenson K M,Wells J S,et al.Accurate frequency of molecular transitions used in laser stabilization:the 3.39 mm transition in CH4 and the 9.33 and 10.18 μm transiton in CO2 [J].Appl.Phys.Lett.,1973,22:192.

[3] Jennings D A,Pollock C R,Peterson K R,et al.Direct frequency measurement of the I2-stabilized He-Ne 473 THz (633 nm) laser [J].Opt.Lett.,1984,8:136.

[4] Quinn T J.Documents concerning the new definition of the metre [J].Metrologia,1984,19:163.

[5] Quinn T J.Practical realization of the definition of the metre (1997)[J].Metrologia,1990,36:211.

[6] BIPM [R],Report,2001.

[7] Hansch T W.High resolution spectroscopy of hytrogen.in The Hydrogen Atom [M].eds.Bassani G F.Inguscio M,Hansch T W.Heideberg:Springer,1989.

[8] Udem T,Reichert J,Holzwarth R,et al.Accurate measurement of large optical frequency differences with a mode-locked laser [J].Opt.Lett.,1999,24:881-883.

[9] Jones D J,Diddams S A,Ranka J K,et al.Carrier-envelope phase control of femtosecond mode-locked lasers and direct optical frequency synthesis [J].Science,2000,288:635-639.

[10] Diddams S A,Jones D J,Ma L,etal.Optical frequency measurement across a 104 THz gap with a femtosecond laser frequency comb [J].Opt.Lett.,2000,25:186.

[11] Reichert J,Niering M,Holzwarth R,et al.Phase coherent vacuum-ultraviolet to radio frequency comparison with a mode-locked laser [J].Phys.Rev.Lett.,2000,84:3232.

[12] Cundiff S T,Ye J,Hall J L.Optical frequency synthesis based on mode-locked lasers [J].Rev.Sci.Instrum.,2001,72,1-23.

[13] Diddams S A,Udem T,Vogel K R,et al.A compact femtosecond-laser-based optical clock [C] ∥ Proc.SPIE,2001,4269:77.