Layered Semiconductor Bi2O2Se for Broadband Pulse Generation in the Near-Infrared

We have studied the broadband nonlinear optical properties of layered semiconductor Bi
₂
O
₂
Se prepared by the modified Bridgman method. The saturable absorber exhibits a modulation depth of 12.2%, a nonsaturable loss of 62.2%, and a saturable intensity of 26 MW/cm
²
at 1.55 μm. With respect to 2-μm band, the absorber shows a modulation depth of 9.1%, a nonsaturable loss of 71%, and a saturable intensity of 44.2 MW/cm
²
. In addition, mode-locked Er-fiber laser and Q-switched Tm-fiber laser employing the saturable absorber were first demonstrated at 1.55 and 2 μm, respectively. Our experimental results have revealed that the Bi
₂
O
₂
Se can be a promising broadband saturable absorber for pulsed lasers in the near-infrared range.