Effect of Convection on the Distortion of Spatial Self-Phase Modulation Pattern in Graphene Dispersions

Abstract

Effect of convection on the distortion of spatial self-phase modulation(SSPM)pattern in graphene dispersions has been investigated. When a Gaussian laser beam is transmitted through grapheme dispersions, the interference pattern in the far-field first forms a series of circular rings, but the upper half of the rings collapses rapidly after a period of time, forming a stable distorted pattern. Experimental results show that thermal convection effect plays a dominant role for the distortion of the SSPM pattern. In the absence of convection in the beam cross section, the interference rings are circularly symmetric rings. In the presence of convection in the beam cross section, the interference rings exhibit circularly asymmetric rings. Theoretical analyses have then been given for the reason of the interference rings distortion. Convection can effectively change the spatial symmetry distribution of polarized graphene sheets and non-linear refractive index in the beam cross-section, thus making the interference rings distortion based on the spatial self phase modulation. It is concluded that the distortion of the interference pattern is originated from the thermal convections induced by laser heating.

Synthesis, Green Photoluminescence and Studies of Nonlinear Optical Spatial Self Phase Modulation Effect in 2D Ga2Te3 Nanosheets

“…1,17,22,23 Interestingly, the origin of the NLO effects in 2D materials, i.e., whether it is contributed from electron/hole coherence or thermal lensing depends on its thermal conductivity and optical absorption at the pump wavelength. 18,24,25 Also, the type of contribution to nonlinearity can be decided from the nature and formation dynamics of the SSPM ring patterns. 24 Herein, the liquid phase exfoliation (LPE) technique has been used for the first time to synthesize atomically thin 2D Ga 2 Te 3 , and the structural and linear optical properties of the synthesized material have been explored using standard characterization tools.…”

“…The SSPM effect in 2D materials is closely associated with the confinement of charge carriers, and the obtained results can be correlated with the electronic parameters of the materials. ,, Being atomically thin, 2D materials show decent light–matter interactions, which opens a new door for the fabrication of photonic devices. Recently, there has been a renaissance in investigating the NLO effect of 2D materials by employing the SSPM effect with the futuristic aim of developing photonic devices for all-optical switching and light modulations. ,,, Interestingly, the origin of the NLO effects in 2D materials, i.e., whether it is contributed from electron/hole coherence or thermal lensing depends on its thermal conductivity and optical absorption at the pump wavelength. ,, Also, the type of contribution to nonlinearity can be decided from the nature and formation dynamics of the SSPM ring patterns …”