Buldt, J.J.BuldtStark, H.H.StarkMüller, M.M.MüllerGrebing, C.C.GrebingJauregui, C.C.JaureguiLimpert, J.J.Limpert2022-05-062022-05-062021https://publica.fraunhofer.de/handle/publica/41613310.1364/OL.4423742-s2.0-85117374742We present a high-power source of broadband terahertz (THz) radiation covering the whole THz spectral region (0.1-30 THz). The two-color gas plasma generation process is driven by a state-of-the-art ytterbium fiber chirped pulse amplification system based on coherent combination of 16 rod-type amplifiers. Prior to the THz generation, the pulses are spectrally broadened in a multipass cell and compressed to 37 fs with a pulse energy of 1.3 mJ at a repetition rate of 500 kHz. A gas-jet scheme has been employed for the THz generation, increasing the efficiency of the process to 0.1%. The air-biased coherent detection scheme is implemented to characterize the full bandwidth of the generated radiation. A THz average power of 640 mW is generated, which is the highest THz average power achieved to date. This makes this source suitable for a variety of applications, e.g., spectroscopy of strongly absorbing samples or driving nonlinear effects for the studies of material properties.en620535Gas-plasma-based generation of broadband terahertz radiation with 640 mW average powerjournal article