Q-switched fiber laser with tunable wavelength operation utilizing a nonlinear saturable absorption of vanadium pentoxide

Abstract

Q-switched fiber laser with a tunable wavelength output is experimentally demonstrated utilizing a nonlinear saturable absorption of vanadium pentoxide (V2O5) in conjunction with a tunable bandpass filter (TBF). The V2O5 saturable absorber (SA) was prepared by mixing V2O5 with polyethylene glycol. The SA film exhibits a modulation depth of 7% with a saturation intensity of 90 MW/cm2. By integrating the SA into an erbium-doped fiber laser cavity while controlling the passband wavelength of the TBF, a Q-switched pulsed laser is realized with a tunable wavelength range of 30 nm that extends from 1535 to 1565 nm. At 1565 nm operation, the laser exhibits the highest slope efficiency of 8.31%. The repetition rate varies from 13.32 to 15.25 kHz, while the pulse width shrinks from 21.3 10 12.75 μs when the pump power rises from 14.9 to 37.7 mW. The pulse energy is 102.6 nJ at the maximum pump power of 37.7 mW. This is the first demonstration of a tunable Q-switched fiber laser operating in a 1.5 μm wavelength region utilizing V2O5 SA.