Generation and amplification of light pulses of less than 50 fs duration at a repetition frequency of 10 kHz

Light pulses of wavelength of 620 nm, duration of 40 fs, and energy 4 X 10^{– 11} J, generated in a ring rhodamine 6G laser with passive mode locking, were amplified to an energy of 5 X 10^{– 7} J in a specially developed multipass amplifying stage pumped by a copper vapor laser. The pump power was less than 1 W when the pulse repetition frequency was 10 kHz. The duration of the amplified pulses was 45 ± 5 fs and the divergence was twice the diffraction limit. A femtosecond continuum was generated in the wavelength range 380–720 nm.