One-dimensional Bi2Te3 nanowire based broadband saturable absorber for passively Q-switched Yb-doped and Er-doped solid state lasers

The broad saturable absorption of topological insulator Bi2Te3 nanowires is presented for the first time, as well as the passively Q-switched pulse operations on both Yb-doped and Er-doped bulk laser with a bandwidth over about 1.7 mu m. Uniform Bi2Te3 nanowires with a large aspect ratio have been synthesized using ultrathin Te nanowires as the template. The broad absorption spectrum from visible to middle infrared reveals a broad optical response. In a 1.0 mu m Yb-doped laser, a pulse width of 303 ns with a pulse energy of 1.2 mu J is achieved. While at Er-doped mid-infrared 2.79 mu m, the shortest pulse width and largest pulse energy are tested to be 444 ns and 5 mu J, respectively. Those results reveal the topological insulator Bi2Te3 nanowire to be a reliable broad optical switcher for solid state lasers in near-and mid-infrared bands. As far as we know, it is for the first time that TIs based solid state lasers at mid-infrared region are reported. Furthermore, this work can be extendable to explore TIs with other nanstructures for application as optoelectronic devices. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement