Sets of microlens arrays to finely shape homogenized focal spots

This study aims to demonstrate the effectiveness of sets of microlens arrays to homogenize and finely shape focal spots, for optimizing optical pumps of interest for Yb-doped slabs in the field of high-power lasers, or for use in materials processing and industrial applications. Homogenization basically involves optical integration in the Fourier plane of a large focusing lens, the input light source being consistently sampled. The generic capabilities of three complementary optical designs are demonstrated thanks to combining transfer-matrix computations with highly resolved ray-tracing modeling. This helps to benchmark a variety of experimental results. Fully generic trends are evidenced in terms of the shaping capabilities, for highly efficient focusing, in the form either of a single spot or of multiple sub-spots. Peak power densities as elevated as some hundreds of kW/cm2 or a few MW/cm2, respectively, may be produced by a couple of multi-kilowatt diode stacks.