Gold nanostars as a Q-switcher for the mid-infrared erbium-doped fluoride fiber laser.

Abstract

We demonstrated passively Q-switched mid-infrared (mid-IR) erbium-doped fiber lasers by using gold nanostars (GNSs) as the Q-switcher. The nonlinear optical responses of the GNSs synthesized via the seed-mediated method have been characterized via a Z-scan technique, and the modulation depth and saturation intensity of the GNSs are measured to be 25% and 15.75 kW/cm2, respectively. The Q-switched fiber laser can deliver a maximum average power of 454mW with corresponding pulse energy of 3.6μJ and pulse duration of 536ns at a repetition rate of 125kHz under the incident pump power 3.5W. To the best of our knowledge, this is the first Letter that reports that the GNSs can act as a Q-switcher for the mid-IR erbium-doped ZBLAN fiber lasers. This Letter can deepen the understanding of the nonlinear optical behavior of the gold nanomaterials and may make inroads for the excellent mid-infrared optoelectronic devices.