Fully planar solar-pumped fiber laser with 0.1% slope efficiency

A slope efficiency of 0.1% has been achieved for a fully planar solar-pumped fiber laser (SPFL) with a diameter of 30 cm and an output power of 34 mW. The fiber length is constrained to 400 m, but numerical simulations indicate that the maximum laser output power can be elevated to 113 mW by simply extending the length of the fiber and housing it in the same body. The tolerance to the solar tracking error was quantified, and the results demonstrated that more than 80% of the maximum output power can be sustained up to a ±23° tracking error. This study demonstrates the capability of the fully planar SPFL to operate without solar tracking.