Large and layer dependent nonlinear optical absorption of MXene 2D thin films

TL;DR

This study investigates how the nonlinear optical absorption of MXene Ti3C2Tx thin films varies with layer number, revealing a transition from RSA to SA and significant changes in absorption coefficients, which are crucial for photonic device applications.

Contribution

It introduces a solution-based, transfer-free coating method for layer-by-layer MXene films and systematically studies their layer-dependent nonlinear optical properties.

Findings

Nonlinear absorption transitions from RSA to SA with increasing layers.

Absorption coefficient beta varies from positive to negative as layers increase.

Nonlinear absorption decreases with higher laser intensities.

Abstract

As a rapidly expanding family of two dimensional (2D) materials, MXenes have recently gained considerable attention due to their appealing properties. Here, by developing a solution based coating method that enables transfer free and layer by layer film coating, we investigate the layer dependent nonlinear optical absorption of Ti3C2Tx films, an important member of the MXene family. By using the Zscan technique, we characterize the nonlinear absorption of the prepared MXene films consisting of different numbers of monolayers. The results show that there is a strong and layer dependent nonlinear absorption behavior, transitioning from revisable saturable absorption (RSA) to saturable absorption (SA) as the layer number increases from 5 to 30. Notably, the nonlinear absorption coefficient beta varies significantly within this range, changing from 7.13 x 100 cm/GW to -2.69 100 cm/GW. We also characterize the power dependent nonlinear absorption of the MXene films at various incident laser intensities, and a decreasing trend in beta is observed for increasing laser intensity. These results reveal the intriguing layer dependent nonlinear optical properties of 2D MXene films, highlighting their versatility and potential for implementing high-performance nonlinear photonic devices.