Ti3C2Tx quantum dots/polyvinyl alcohol films as an enhanced long-term stable saturable absorber device for ultrafast photonics

Abstract

The challenge related to degradation under ambient conditions has greatly constrained Ti₃C₂T_x quantum dots (QDs) from being used in optical applications. Herein, Ti₃C₂T_x QDs with an average size within 10 nm were synthesized by exploiting the minimally intensive layer delamination united liquid-phase exfoliation methods. Then, polyvinyl alcohol (PVA) was employed to encapsulate Ti₃C₂T_x QDs to prepare a saturable absorber (SA) applied in ultrafast laser systems. As verified by balanced twin-detector measurements, the Ti₃C₂T_x QDs/PVA SA exhibited an ultra-low saturation intensity of 4.3 kW cm⁻². By incorporating the Ti₃C₂T_x QDs/PVA SA into an erbium-doped fiber laser cavity, both Q-switched and mode-locked lasers with high operational stability were easily obtained. Furthermore, the Ti₃C₂T_x QDs/PVA SA could still easily realize the stable passive mode-locked state with the narrowest pulse width of 654 fs beyond 12 months, which sufficiently demonstrates its versatility and long-term stability. Thus, this work provides a facile approach for MXene QD based practical optoelectronic devices.