Terahertz pump — Terahertz probe system at Novosibirsk free electron laser: Commissioning and results of first experiments

A single-color pump-probe system has been commissioned at the Novosibirsk free electron laser facility. Monochromatic laser radiation with a bandwidth of about 1% can be tuned within the spectral ranges of 90–240 and 30–90 μΜ. The laser emits radiation as a continuous stream of 100-ps pulses with a repetition rate of 5.6 MHz. The average radiation power can reach 100 W. The temperature of samples located in a helium cryostat can be varied from 2 up to 325 K. The results of first pump-probe measurements of non-equilibrium dynamics of hot electrons in a Ge:Sb crystal at T=5÷50 K are presented.