Dual-rod pumping concept for TEM-mode solar lasers.

We propose here a novel concept to a large improvement in TEM-mode side-pumped solar laser collection, conversion efficiencies, and brightness figure of merit by pumping two thin laser rods simultaneously, each rod being pumped by half of the solar collector area instead of today's one thick rod scheme pumped by the full solar collector area. A semicylindrical fused silica lens allows an efficient focusing of the concentrated solar power from the focal zone of the parabolic mirror into the two thin laser rods mounted within two compound parabolic concentrator-semicylindrical pump cavities within the same laser head. 17.2 W continuous-wave TEM-mode solar laser power was numerically calculated, corresponding to 11.0  W/m solar laser collection efficiency, 1.31% incoming solar power-to-TEM-mode laser power conversion efficiency, and 14.3 W brightness figure of merit, being 1.39, 1.23, and 2.21 times, respectively, higher than the previous state-of-the-art experimental records.