Stable Emissions from a Four-Rod Nd:YAG Solar Laser with ±0.5° Tracking Error Compensation Capacity

Conventional solar-pumped lasers rely on expensive and highly accurate solar tracking systems, which present a significant economic barrier to both laser research practical applications. To address this challenge, an end-side-pumped four-rod head was designed built for testing at PROMES-CNRS. Solar radiation collected concentrated using heliostat–parabolic mirror system. A fused silica aspheric lens further the rays into flux homogenizer within four Nd:YAG rods were symmetrically positioned around reflective cone cooled by water. Four partially mirrors precisely aligned extract continuous-wave 1064 nm power from each rod. The prototype demonstrated stable multibeam operation with system turned on. Even when off, total output extracted remained 1 min, representing, best of our knowledge, first successful demonstration without tracking. For typical errors up ±0.5°, loss in produced only about 1%, representing 8.0-fold improvement over previous experiments under error conditions.