[19p-431B-1~18] 3.5 Laser system and materials

△ [19p-431B-2] Reduction of oscillation threshold of Nd³⁺doped fiber laser

〇Yuta Yasumatsu¹, Iyoda Mitsuhiro¹, Bisson Jean Francois^2,1, Masuda Taizo^3,1, Endo Masamori¹ (1.Tokai Univ., 2.Moncton Univ., 3.Toyota Motor Co.)

Keywords:fiber laser, laser medium, fiber

This research work aims at achieving solar-pumped laser oscillation without lens concentrator. The intrinsically low power density of solar radiation calls for the use of original laser architectures as well as laser materials with very low losses. A side-pumped Nd⁺³-doped alumino-silicate fiberemitting at around λ=1 µm was chosen owing to its inherent power scalability, its four-level nature and extremely low background loss. However, we found that the exquisitely small thermal population of the lower laser level, ⁴I_11/2, is the dominant loss mechanism. Absorption was measured at room as well as low temperatures. At T= -34 ^oC, absorption is reduced by a factor of four and the threshold of laser oscillation is reduced by a similar amount.