Intense broadband mid-infrared pulses of 280 MV/cm for supercontinuum generation in gaseous medium.

We produce extremely bright mid-infrared (mid-IR) pulses with a tunable wavelength of 7 μm to 15 μm through difference frequency generation. Optimization of beam quality and beam focusing results in an intense mid-IR field spatiotemporally confined in the lambda-cubic volume. A near planar wavefront is achieved through manipulating the wavefront curvature of the pumping pulse in the frequency downconversion process. Coherent mid-IR pulses are produced with the peak field of 280 MV/cm at 10 μm, and its intensity exceeds 100  TW/cm, estimated from measured pulse energy, and spatial and temporal pulse profiles. Interaction of such an intense mid-IR field with Xe and Kr gas forms plasma and generates a supercontinuum in the visible range.