First-Principles Calculations of Bi2Te2 and its Application in Ultrafast Fiber Lasers

This paper analyzes the energy band, the density of states, and optical properties of the ternary compound
$\text{Bi}_{2}\text{Te}2 Se$
by first-principles calculations. It is proved that the material has good light absorption properties. Further,
$\text{Bi}_{2}\text{Te}2 Se$
nanosheets were prepared by a hydrothermal method and used as a saturable absorber in an ultrafast fiber laser, achieving a stable mode-locked pulse output with 1566 nm at a pump power of 32.6 mW. When pump power reaches 116.5 mW, a stably bound state pulse appears in the laser. This study demonstrates that the material is a potential high-performance saturable body, which provides a possibility for developing ultrafast fiber lasers.