[5a-C14-1~8] 3.5 Laser system and materials

[5a-C14-1] Solar pumped fiber laser

〇Taizo Masuda¹, Mitsuhiro Iyoda², Yuta Yasumatsu², Masamori Endo² (1.Toyota motor corp., 2.Tokai Univ)

Keywords:Solar pumped laser, Low-concentrated factor, Fiber laser

We demonstrate an extremely low-concentrated solar-pumped laser (SPL) using a fibre laser with transverse excitation geometry. Low concentration factors in SPLs are highly desired to eliminate the need for precise solar tracking and to considerably increase the number of laser applications. We exploit the intrinsic low-loss property of silica optical fibres to compensate for the extremely low gain coefficient of the weakly pumped active medium. A 40-m-long Nd³⁺-doped silica fibre coil is packed in a ring-shaped chamber filled with a sensitizer solution, which functions as a down-converter. The dichroic top window of the chamber transmits a wide range of sunlight and reflects the down-converted photons, confining them to the highly reflective chamber until they are absorbed by the Nd³⁺ ions. We demonstrate a lasing threshold that is 15 times the concentration of natural sunlight and two orders of magnitude smaller than those of conventional SPLs.