Start-to-end optimization framework for free-electron lasers driven by laser wakefield accelerators

Laser wakefield accelerators (LWFAs) offer a promising route to compact free-electron lasers (FELs), but strong coupling among beam generation, transport, and radiation makes performance highly sensitive to parameter choices.A start-toend framework is thus essential for coherent optimization of the full process.Here, we establish such a framework, integrating LWFA beam generation, transport, and FEL interaction within a unified loop.By incorporating the beamline configuration into the optimization, the framework enables a consistent assessment of overall FEL performance.Using this framework, a representative parameter set suitable for extreme ultraviolet FEL operation is obtained.The optimized beam exhibits a mean energy of approximately 500 MeV, a charge of 34 pC, and a relative energy spread of 0.4% (FWHM).The FEL reaches saturation at 13.5 nm, delivering a pulse energy of 9 µJ and a peak power of 3.3 GW.This work provides a systematic methodology for designing LWFA-driven FELs, advancing compact, accessible systems for diverse applications.