Digital Twin of a One‐Sun‐Driven Luminescent‐Concentrator‐Assisted Planar Solar‐Pumped Fiber Laser

ABSTRACT Planar solar‐pumped fiber lasers (SPFLs) based on luminescent solar concentrators (LSCs) enable direct conversion of one‐sun irradiation into laser radiation. However, experimentally demonstrated performance remains limited, while the underlying mechanisms are insufficiently understood. In this work, a physics‐based digital twin of LSC‐assisted SPFL is developed using Monte Carlo ray tracing with explicit fiber geometry, coupled to rate‐equation and power‐propagation modeling. The model is validated against differential‐gain and laser‐output measurements. The analysis reveals that SPFL performance is constrained by weak photon–core interaction arising from the µm‐scale core and low single‐pass absorption probability in the Nd 3+ ‐doped core. In the experimentally validated configuration, only 0.54% (0.34 W) of the incident power is absorbed within the core, corresponding to 35 mW laser output. Photon‐flux analysis identifies 51.2% material‐related losses and 48.3% cavity‐related confinement losses associated with angular‐dependent dichroic‐mirror performance. Parameter studies demonstrate sensitivity of SPFL performance to sensitizer photoluminescence quantum yield, LSC refractive‐index distribution, sensitizer thickness, and core diameter. Combining several improvement strategies within the present architecture yielded approximately 470 mW laser output and 0.67% solar‐to‐laser conversion efficiency representing 13‐fold improvement relative to the baseline system (0.05%). The developed digital twin enables systematic investigation of alternative architectures and optimization of one‐sun SPFLs.