1.5-micron fiber laser passively mode-locked by gold nanoparticles saturable absorber

A 1.5 μm fiber laser which was passively mode-locked by gold nanoparticles saturable absorber (SA) is proposed and demonstrated. The SA was fabricated via dripping the gold nanoparticles solution onto the fiber ferrules and left to dry. The SA has an insertion loss of 12 dB, modulation depth of 1.35% and saturation intensity of ∼1GW∕cm2. At sufficiently high pump power, the mode-locked operation started with some applied disturbance to the SA. The resultant mode-locked characteristics includes 6.897 MHz of repetition rate, 4.04 ps of pulsewidth, ∼61dB of signal-to-noise ratio and 1.329 mW of output power.