Average power scaling of sub-2 cycle lasers to the kilowatt regime

Double-stage nonlinear compression of state-of-the-art femtosecond fiber lasers allows for few-cycle lasers with record-high average power levels. Here, a comprehensive study on further power scaling aspects is presented. Compression to sub-2cycle pulses is demonstrated and it is shown that capillary waveguides and gold-coated sapphire optics are suitable to realize several 100 W of average power in combination with energetic sub-2cycle pulses in the near future. These lasers could open unique possibilities in high harmonic generation and attosecond science.