Nonlinear absorption property investigation into MAX phase Ti2AlC at 1.9 μm

Abstract

An experimental and theoretical investigation into the nonlinear absorption properties of MAX phase Ti2AlC was conducted at 1900 nm wavelength. First, the nonlinear absorption coefficient measurement of Ti2AlC was carried out using an open-aperture (OA) Z-scan technique. This measurement revealed that the nonlinear absorption coefficient of Ti2AlC was ∼(-24.13×103) cm2/GW at 1900 nm. Subsequently, the energy band structure of the Ti2AlC was calculated through density functional theory (DFT) calculation. This calculation confirmed that Ti2AlC had a metallic band structure implying an ultrawide absorption bandwidth. Finally, the feasibility of fabricating an all-fiberized device of a saturable absorber (SA) using Ti2AlC was conducted with a side-polished fiber platform. The SA was successfully used for the generation of femtosecond soliton pulses with features of 17.91 MHz repetition rate, 4.3-nm bandwidth, and ∼960 fs pulse width at 1922 nm. To the best of authors’ knowledge, this is the first demonstration of the use of a MAX phase-based SA for femtosecond mode-locking in the 1.9 μm spectral region.