Enabling scalable inertial fusion energy with next-generation diode laser pump modules

Unlocking inertial fusion energy (IFE) demands laser technologies that are not only powerful, but also reliable and scalable. This paper introduces a new class of high-power diode laser pump modules tailored for solid-state lasers like Nd:glass and Yb:YAG, which are key components in laser-driven fusion systems. The proposed pump module concept is based on a modular and scalable architecture that simplifies system integration and enables flexible power scaling to address the evolving requirements of fusion technology demonstrators and future power-plant-class lasers. Pump modules delivering optical peak powers below 1 MW can be realized using mature diode laser bar and stack technologies, providing a robust and low-risk pathway for near-term demonstrators. Current implementations utilize 500 W-class diode bars with electro-optical efficiencies exceeding 60%, while the development roadmap targets efficiencies of 70%. Scaling pump modules toward the megawatt power class imposes additional constraints at the component and architecture level. In particular, bar-level peak powers of ≥ 1 kW combined with low-pitch stack architectures are required to achieve the pump power densities needed for compact optical pump engines. Recent advances demonstrating bar-level outputs up to 2 kW highlight substantial headroom for further scaling within this framework. A key requirement for these systems is the uniform excitation of large-aperture gain media, essential for meeting the stringent performance standards of fusion-class lasers. To achieve this, the pump system will provide a homogenized beam profile with adaptable dimensions from 20×20 mm² to 85×85 mm², ensuring consistent energy distribution across the gain medium. The proposed technology combines high optical output power with excellent efficiency and a compact footprint, positioning it as a cornerstone for scaling future laser architectures beyond the limitations of lamp-pumped designs.