Long-lifetime gain media as a path to low-cost high-energy lasers

High-energy, low-repetition-rate ( 10 – 100 Hz), pulsed solid-state lasers are essential for applications such as laser-driven fusion, and advanced laser manufacturing. While Yb-doped gain media like Yb:YAG have been extensively modeled and deployed, their short upper-state lifetimes or fluorescence lifetime ( ∼ 0.95 ms) lead to significant inversion decay between pulses, requiring high peak pump power and capital-intensive diode stacks. Here, we present a simulation comparison of the performance of Tm:YLF and Yb:YAG amplifiers. In a first step the model is validated against published experimental data for Tm:YLF and Yb:YAG amplifier. The model is then used for performance optimization of the amplifier configuration and highlights Tm:YLF’s key advantage: a long upper-state lifetime ( ∼ 15 ms), enabling near-complete energy storage and ∼ 2 × fewer pump diodes for multi-joule pulses compared to Yb:YAG. This work provides design guidelines for scalable Tm:YLF systems for low-rep-rate, high-energy operation.