Light Management for Enhancing Optical Gain in a Solar‐Pumped Fiber Laser Employing a Solid‐State Luminescent Solar Concentrator

Optical gain of 8.3 km−1 is obtained in a neodymium-doped silica fiber under simulated sunlight (intensity = 2.1 kW m−2). The medium (length 50 m) coiled and attached to solid-state luminescent solar concentrator (LSC) disk (diameter 180 mm). disk/fiber unit placed cavity comprising highly reflective (HRM) dichroic (DM) mirrors increase the photon confinement by factor 2.2 compared with liquid LSC (also employing HRM/DM). enhancement mainly due air gap between HRM/DM LSC, which affords total internal reflection (TIR) an ideal boundary condition for multilayer mirrors. numerical calculations indicate that additional 2.2-times achievable side wall exhibiting 90% diffuse reflection. This has been experimentally confirmed (1.9-times optical-gain realized adding polytetrafluoroethylene side-wall reflector). Overall, LSC-based solar-pumped laser (SPL) walls exhibits 4.2, superior its liquid-state predecessor. Further improvements design optimization will facilitate market penetration SPLs.