Mode-locked laser with a repetition rate of 17.6 THz.

In 2001, a concept was proposed to generate mode-locked ultrashort laser pulses with a repetition rate in excess of 10 THz [Phys. Rev. Lett.87, 223901 (2001)PRLTAO0031-900710.1103/PhysRevLett.87.223901], which has not been demonstrated so far. In the present research, the concept is experimentally demonstrated using a dispersion-compensated high-finesse cavity filled with hydrogen gas. Second-order intensity autocorrelation is used for distinguishing two cases with and without mode-locking as well as for characterization of the temporal profile. Mode-locked sub-30-fs pulses with a repetition rate of 17.6 THz are synthesized by continuous-wave laser lines generated via stimulated Raman scattering and four-wave Raman mixing induced in the high-finesse cavity.