Switchable nonlinear optical isolator in MXene

We investigate the microdynamics of MXene (Ti3C2Tx) flakes under the influence of two opposing effects: light-induced alignment and Brownian motion. The interplay between these effects gives rise to spatial self-phase modulation patterns. Light-induced alignment initiates the formation of diffraction rings, while Brownian motion acts to counter this process. The dominance of each effect is governed by the optical absorption property of the solvent. Leveraging this mechanism, we develop a switchable nonlinear optical isolator using a single-phase MXene dispersion. Upon application of a control beam, the device transitions from a nonlinear optical isolator that exhibits ring patterns in only one direction to a symmetric configuration that displays ring patterns in both directions. This simple device holds promises for applications in optical switching and logic operations.