Laser-induced dynamic alignment and nonlinear-like optical transmission in liquid suspensions of 2D atomically thin nanomaterials

Abstract

Nonlinear optical property of atomically thin materials suspended in liquid has attracted a lot of attention recently due to the rapid development of liquid exfoliation methods. Here we report laser-induced dynamic orientational alignment and nonlinear-like optical response of the suspensions as a result of their intrinsic anisotropic properties and thermal convection of solvents. Graphene and graphene oxide suspensions are used as examples, and the transition to ordered states from initial optically isotropic suspensions is revealed by birefringence imaging. Computational fluid dynamics is performed to simulate the velocity evolution of convection flow and understand alignment-induced birefringence patterns. The optical transmission of these suspensions exhibits nonlinear-like saturable or reverse saturable absorptions in Z-scan measurements with both nanosecond and continuous-wave lasers. Our findings not only demonstrate a non-contact controlling of macroscopic orientation and collective optical properties of nanomaterial suspensions by laser but also pave the way for further explorations of optical properties and novel device applications of low-dimensional nanomaterials.

Spatial Self-Phase Modulation of Optical Vortex Beams in Liquid Suspensions of Semiconducting, Semimetallic, and Metallic 2D Nanoflakes due to a Kerr-like Nonlinearity

“…However, the authors of ref neglected the thermal effects even though they used CW and high repetition-rate sources to perform the experiments. Moreover, it has already been shown that thermal effects can also lead to the alignment of two-dimensional structures at the same time that it induces thermo-optical nonlinearities, reinforcing the importance of thoroughly analyzing the physical mechanisms responsible for the observed phenomenon to avoid mistaken inferences about the optical properties of the materials.…”

Investigating the nonlinear optical response of virgin cherry kernel oil and its application to detecting adulteration

“…When SSPM originates from the electronic or molecular orientation of nonlinear media, it relates to the real part of third-order electronic susceptibility ( ( ) 3 c ) [38]. However, as discussed in [39], relying on the relationship between ( ) 3 c and n 2 is often erroneous. The optical nonlinearity associated with thermal effects does not originate from electronic contributions, but does have an intensity dependence, which can be expressed as n n I, th th 2,…”