Ultrafast Nonlinear Optical Properties and Carrier Dynamics of $Ta_{4}C_{3}T_{x}$ and $Mo_{2}Ti_{2}C_{3}T_{x}$ MXene Nanosheets

Materials exhibiting strong nonlinear optical (NLO) properties along with fast carrier recovery have fostered significant advancements in photonic devices, enabling the development of ultrafast lasers, optical limiters, optical switches, modulators, photodetectors, and more. Among these materials, transition metal carbides, nitrides, and carbonitrides (MXenes), characterized by the general formula <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{M}_{\mathrm{n}+1}\mathrm{X}_{\mathrm{n}}\mathrm{T}_{x}$</tex> (where M is a transition metal, X is C or N, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{T}_{x}$</tex> represents surface terminated groups such as -OH, -O, or -F), are particularly attractive for such applications due to their exceptional NLO response, broadband absorption, ultrafast carrier relaxation, and resistance to radiation and heat.