Indium selenide saturable absorber for high-energy nanosecond Q-switched pulse generation.

As a kind of III/VI group compound 2D layered material, indium selenide (In2Se3) has attracted tremendous interest because of its favorable optoelectronic characteristics. Here, magnetron sputtering deposition (MSD) technology was employed to prepare an In2Se3-based saturable absorber (SA). The nonlinear optical properties of this SA, whose modulation depth (ΔT) is 6.18%, were studied. With the aid of its saturable absorption, a stable two-wavelength Q-switching Er-doped fiber (EDF) laser was established. When pump power was adjusted to 900 mW, the output power was increased to 63.84 mW. The shortest pulse duration and maximum pulse energy were estimated to be 556 ns and 376 nJ, respectively. The signal-to-noise ratio of 70 dB proves this fiber laser has high stability. In comparison with previous works, the laser performance in this study is improved significantly. These results indicate that the In2Se3 holds promise as an outstanding candidate for high-energy pulse generation and will advance the development of In2Se3-based nonlinear photonics devices.