抄録
We observed laser oscillation for a multimode Nd-doped fiber laser with D-shaped cladding under quasi-solar-pumping simulated by an intense halogen lamp with a color temperature of 5,600 Kelvin. The fiber had a millimeter-scale diameter and was 78 m long, and the doping rate was 3000 ppm of Nd ions in silica core-glass. Results show that the output power obtained was 300 mW when the injected power of the lamplight was 1.1 W at an entrance to the fiber, and the optical-optical conversion efficiency was 27 %. The threshold of laser oscillation is 24 times for the solar constant (0.14 W/cm2), a value which is one order of magnitude lower than the case of crystal lasers reported under solar-pumping.
