Self-compression to sub-3-cycle duration of mid-IR optical pulses via nonlinear propagation in bulk

Here, we demonstrate efficient and clean self-compression via nonlinear propagation of mid-IR pulses in bulk. The optical pulses used of the experiments were produced in a home-built OPCPA delivering 67 fs duration pulses at up to 3.2 W average output power and 160 kHz repetition rate. For the experiment, 3 μJ of the 20 μJ available were used. Upon attenuation, the output beam of the OPCPA system was focused by a 10 cm focal length CaF₂ lens into a 3 mm thick uncoated YAG plate placed on a translation stage. The plate was translated within the focal region and Frequency Resolved Optical Gating (FROG) traces were recorded and the pulse duration was retrieved for each position of the plate.