  Strong mid-infrared light-matter interaction has attracted extensive
attention as it opens up new frontiers in nonlinear optics. Here we observe
through simulations a novel aspect of mid-infrared pulse dynamics in a
high-pressure gas-filled capillary, where a pulse with a power well below the
critical power for Kerr self-focusing undergoes an astonishing rise of the peak
intensity following an extremely efficient spectral broadening. This intensity
enhancement is attributed to the Kerr-induced focusing of the supercontinuum.
Our study provides an interesting perspective for controlling the laser
intensity with possible applications in nonlinear light conversion driven by
mid-infrared pulses.
