In order to improve the output power of solar-pumped single-crystal fiber (SCF) lasers, a novel solar concentrating system is proposed, which consists of a parabolic mirror, a 3D-CPC, and a hollow-core reflector. By ray tracing with TracePro, influence of the fiber’s diameter and the hollow reflector’s shape on the solar absorption efficiency is theoretically investigated. A typical Nd:YAG SCF with a core-diameter of 1 mm, length of 150 mm and doping concentration of 1 at.%...