Аннотация:We report the application of a newly developed femtosecond fiber laser for the THz time-domain spectroscopy. Ytterbium doped fiber was used for generation of laser pulses at wavelength 1.06 mum with the further amplification. The use of novel SESAM (semiconductor saturable absorber mirror) device made it possible to get pulse duration less than 200 fs on the 3 average power up to 1 W at the 50 MHz pulse repetition rate. We analyze the nonlinear and semiconductor devices optimal for the generation and electro optical detection of THz pulses in the time-domain systems based on the femtosecond ytterbium fiber laser.