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Title: Tunable effective nonlinear refractive index of graphene dispersions during the distortion of spatial self-phase modulation

Spatial self-phase modulation (SSPM) was observed directly when a focused He-Ne laser beam at 633 nm went through liquid-phase-exfoliated graphene dispersions. The diffraction pattern of SSPM was found to be distorted rapidly right after the incident beam horizontally passing through the dispersions, while no distortion for the vertically incident geometry. We show that the distortion is originated mainly from the non-axis-symmetrical thermal convections of the graphene nanosheets induced by laser heating, and the relative change of nonlinear refractive index can be determined by the ratio of the distortion angle to the half-cone angle. Therefore, the effective nonlinear refractive index of graphene dispersions can be tuned by changing the incident intensity and the temperature of the dispersions.
Authors:
; ; ; ; ;  [1] ;  [2] ;  [3] ; ;  [1] ;  [4] ;  [2]
  1. Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)
  2. State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)
  3. (Iraq)
  4. (CRANN), Trinity College Dublin, Dublin 2 (Ireland)
Publication Date:
OSTI Identifier:
22261560
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; DISPERSIONS; GRAPHENE; HELIUM-NEON LASERS; NANOSTRUCTURES; NONLINEAR PROBLEMS; REFRACTIVE INDEX