LAUSR

We report a solar pumped solid state laser using a 20 mm long, 3 mm diameter neodymium-doped yttrium aluminum garnet laser rod. This rod was placed in a liquid cooling chamber using a water-white-emulsion-paint mix. This mix provides cooling for the laser crystal and also doubles as a diffuse light scattering liquid. This enhances sunlight scattering and leads to a greater absorption in the laser rod. We numerically model the solar absorption in the laser rod using a ray-tracing model and predict a 2.6 times enhancement in absorption when a 98% reflective diffuse scatter is modelled compared to 0% scattering. We experimentally demonstrated this, showing a 2.58 times increase in average output power of the solar laser compared to the use of pure water as a cooling liquid. Using the water-white-paint scattering cooling liquid, we demonstrated a laser with an output power of 2.3 W and with a collection efficiency of 27.5  W/m2.