Heterostructures of Ti₃C₂T_x–Bi₂Te₃ Nanosheets as Saturation Absorbers for Femtosecond Pulse Generation

Two-dimensional (2D) nanomaterials have immense potential in ultrafast laser applications due to their excellent optical characteristics. However, the low modulation depth of individual materials obstructs enhancement of the laser pulse output, which limits the application of individual materials. Therefore, we prepared a Ti 3 C 2 T x –Bi 2 Te 3 vertical heterostructure (TB-VHS) using ultrasound-assisted methods to overcome the limitations of the individual materials. Various functional groups in Ti 3 C 2 T x lead to the formation of heterogeneous structures of different systems at the interface between Ti 3 C 2 T x and Bi 2 Te 3 . The transfer of strong interlayer carriers exhibits excellent nonlinear-optical properties. The modulation depth of TB-VHS was ∼8.2 times that of Ti 3 C 2 T x and 2.5 times that of Bi 2 Te 3 . Furthermore, TB-VHS was used as a saturable absorber (SA) to realize stable conventional soliton pulses with a pulse duration of 547 fs under 1557.76 nm. Our results indicate that Ti 3 C 2 T x –Bi 2 Te 3 heterostructures are promising SAs for pulsed-laser applications.