Nonlinear pulse compression to 43 W GW-class few-cycle pulses at 2 μm wavelength.

High-average power laser sources delivering intense few-cycle pulses in wavelength regions beyond the near infrared are promising tools for driving the next generation of high-flux strong-field experiments. In this work, we report on nonlinear pulse compression to 34.4 μJ-, 2.1-cycle pulses with 1.4 GW peak power at a central wavelength of 1.82 μm and an average power of 43 W. This performance level was enabled by the combination of a high-repetition-rate ultrafast thulium-doped fiber laser system and a gas-filled antiresonant hollow-core fiber.