Effect of bending on emission characteristics of large core Yb/Al doped optical fiber with depressed cladding structure

The large core Yb/Al doped optical fiber with depressed cladding structure for fiber laser applications was fabricated. The measured bending loss was found to increase to 0.11 dB m(-1) with the decrease of bending diameter to 60 mm and then increase sharply to 1.25 dB m(-1) down to 10 mm. The broad emission band appeared from 1000 nm to 1100 nm upon pumping with the 976 nm laser diode. When the light pumping with launching onto the place between the depressed cladding and the low-index polymer coating, the emission of similar to 4.50 dB increased at the bending diameter of 60 mm, the optimum bending diameter for an efficient pumping.