Designing Optical Concentrator Targets for High-Intensity Lasers

A structured target that can act as a plasma mirror to concentrate the final focus of a high-power laser beam, thereby increasing the intensity, would be extremely useful for a variety of applications. In this work we investigate the design of an optical concentrator for improving laser coupling into a micrometer-scale waveguide-like channel. Laser–microchannel interactions have shown potential as a platform for laser-based particle acceleration in computational studies and experiments on the Texas Petawatt and OMEGA EP Laser Systems, but laser-coupling efficiency is limited by pointing stability. Compound parabolic concentrators have been used previously to increase high-power laser intensity on target. However, novel optical concentrator shapes can be optimized for use with realistic focused high-power laser profiles. We present designs of concentrator targets for use in experiments on OMEGA EP and investigate their effectiveness for microchannel experiments. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856 and the Department of Energy under Award Number DE-SC0020431.