Continuous wave laser-induced nonlinear optical properties of nanofluids based on graphene quantum dot

This work reports the third-order nonlinear optical study of graphene quantum dot-based nanofluid. Graphene quantum dots have proved their superiority over conventional semiconductor quantum dots in a wide range of applications. However, the experimental probe of their third-order nonlinear optical properties for photonics application remains scarce. The structural, morphological and compositional analysis of the graphene quantum dot nanofluids was achieved using Transmission electron microscopy, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The excellent linear optical properties were revealed through UV–visible absorption spectroscopy along with Photoluminescence spectroscopy. Z-scan technique utilizing a continuous wave laser at 532 nm wavelength was employed to study the third-order nonlinear optical properties of the material. Open-aperture and closed-aperture Z-scan measurements, respectively, display the reverse saturable absorption and self-defocusing effect. The nonlinear absorption coefficient β , nonlinear refractive index n 2, and third-order nonlinear susceptibility obtained in the order of 10 –4 cm/W, 10 –9 cm 2 /W and 10 –6 e.s.u are comparable with those of graphene-based materials reported. Thus, this study proves the potential of graphene quantum dot nanofluids in optoelectronic applications.