All-fiberized, passively Q-switched 1.06 μm laser using a bulk-structured Bi2Te3 topological insulator

We experimentally demonstrate the use of a bulk-structured Bi2Te3 topological insulator (TI) deposited on a side-polished fiber as an effective saturable absorber for the implementation of an all-fiberized passively Q-switched 1.06 mu m fiber laser. Unlike previous Q-switched laser demonstrations based on nanosheet-based TIs, which require complicated and sophisticated fabrication procedures, a similar to 9.1 mu m-thick bulk-structured Bi2Te3 TI film that was prepared using a mechanical exfoliation method was chosen to be used in this experimental demonstration due to ease of fabrication. The modulation depth of our prepared bulk-structured Bi2Te3 TI-deposited side-polished fiber was measured to be similar to 2.5% at 1.06 mu m. By incorporating such an absorber in an all-fiberized ytterbium-doped fiber ring cavity, stable Q-switched pulses were obtained through evanescent field interaction between the oscillated beam and the Bi2Te3 TI film. The temporal width and repetition rate of the output pulses were tunable from similar to 1 to similar to 1.3 mu s and from similar to 77 to similar to 35 kHz, respectively, depending on the pump power. Through a performance comparison of our laser with recently demonstrated Q-switched 1 mu m fiber lasers using carbon nanotubes, graphene, and nano-structured TIs, our bulk-structured Bi2Te3 TI-based saturable absorber is shown to have passive Q-switching performance comparable to saturable absorbers based on carbon nanotubes or nano-structured TIs.