Generation of wavelength-tunable few-cycle pulses in the mid-infrared at repetition rates up to 10 kHz.

We demonstrate a compact and tunable mid-infrared light source that provides carrier-envelope-phase (CEP)-locked pulses at repetition rates from 500 Hz to 10 kHz. The seed pulses were generated by intra-pulse difference frequency mixing of the output of an Yb:KGW regenerative amplifier that had been spectrally broadened by continuum generation using multiple plates. Then, a two-stage optical parametric amplifier was used to obtain output energies of about 100 µJ/pulse for center wavelengths between 2.8 and 3.5 µm. Owing to the intense pulse energies, it was possible to compress the multi-cycle pulses down to two-cycle pulses using YAG and Si plates.