Comparative analysis of solar pumped Nd:YAG lasers with internal and external sensitizers

We compare the capabilities of external and internal sensitizers in solar laser systems through numerical simulations. Three lasing media were studied: Nd:YAG, Nd:YAG with alexandrite as an external sensitizer, and Cr:Nd:YAG with Cr3+ ions as internal sensitizers. The Nd:YAG + alexandrite system showed a 1.38-fold efficiency gain over Nd:YAG without sensitizer, while Cr:Nd:YAG achieved a 1.34-fold improvement due to both radiative and nonradiative transfer mechanisms. Thermal analysis revealed that Cr:Nd:YAG becomes inoperative at input powers above 2.3 kW, whereas Nd:YAG and Nd:YAG + alexandrite remained stable up to 2.9 kW. It was shown that configurations based on external sensitization, in particular the Nd:YAG + alexandrite system, can provide both increased efficiency and excellent thermal stability, which offers clear advantages for high-power and long-term operation of solar lasers.