Evaluation of white-light generation as possible seed for a mid-infrared optical parametric chirped pulse amplifier

Abstract: White-light spectra of different crystals, based on 1030-nm intense pump pulses have been investigated in order to derive a near-infrared seed for mid-infrared generation. Among ten crystals, YAG (yttrium aluminium garnet), KGW (potassium gadolinium tungstate) and YVO4 (yttrium orthovanadate) exhibit the most suitable properties for supercontinuum generation with high efficiency for spectral broadening as well as high tolerance to optical damage. Numerical simulations of laser induced filamentation, a dynamic balance between self-focusing and plasma defocusing resulting in supercontinuum generation, have been carried out to interpret and support our results theoretically. The simulations are in fair agreement with experimental results and they support the finding that low-bandgap materials like YVO4, YAG and KGW seem to be better suited than high-bandgap materials, like fused silica and fluorides.