The groundbreaking research, titled “Emerging Ta4C3 and Mo2Ti2C3 MXene Nanosheets for Ultrafast Photonics,” published in Advanced Optical Materials, was carried out by scientists at the Institute of Electronic Structure and Laser (IESL – FORTH) - Michalis Stavrou, Maria Farsari, and David Gray - in collaboration with Benjamin Chacon, and Yury Gogotsi from Drexel University, as well as Anna Maria Pappa and Lucia Gemma Delogu from Khalifa University of Science and Technology.

Overview

The researchers found that Ta₄C₃Tₓ and Mo₂Ti₂C₃Tₓ MXenes exhibit exceptional ultrafast nonlinear optical (NLO) properties and carrier dynamics, as investigated using Z-scan and pump-probe optical Kerr effect techniques with femtosecond laser pulses in the visible and infrared ranges. They reported that the NLO responses of these materials surpass those of all previously studied MXenes and most other 2D nanomaterials, reaching remarkably high third-order susceptibility (χ⁽³⁾) values on the order of 10⁻¹³ esu. It was observed that Mo₂Ti₂C₃Tₓ demonstrated the strongest NLO response under both excitation regimes, which was attributed to charge transfer between the Mo and Ti layers in its structure. Under visible excitation, the MXenes showed pronounced saturable absorption, while under infrared excitation, they exhibited strong reverse saturable absorption, enabling effective optical limiting. Additionally, the pump-probe experiments revealed two distinct relaxation processes: a fast one occurring on the sub-picosecond timescale and a slower one a few picoseconds after photoexcitation. The researchers concluded that these MXenes rank among the most powerful NLO materials known, highlighting their significant potential for use in advanced photonic and optoelectronic applications, such as laser technologies, optical protection, telecommunications, and optical or quantum computing.

Reference: Stavrou, M. et al. Emerging Ta4C3 and Mo2Ti2C3 MXene Nanosheets for Ultrafast Photonics. Advanced Optical Materials 13 (2025). https://doi.org/10.1002/adom.202403277 [1]