Tunable High-Power Q-Switched Fiber Laser Based on BP-PVA Saturable Absorber

Black phosphors (BP) nano-materials have been extensively investigated in the past years. However, the character of easily oxidizable limits BP's stability. Here a long-term-stable tunable Q-switched fiber laser with BP polymer composite (polyvinyl alcohol, PVA) as saturable absorber is realized. The modulation depth and the saturation power intensity of the BP-PVA film are 8.3% and 7.9 MW/cm2, respectively. A high average output power of 12.03 mW is obtained under the pump power of 400 mW. The shortest pulse width and maximum single pulse energy are 1.365 μs and 148.63 nJ, respectively. Meanwhile, the output spectra have a 2.5-nm blue shift when the pump power increases. The results prove that as a Q-switcher, BP polymer composite has a good performance on high power and excellent stability pulsed laser.