Fabrication of covalently functionalized graphene oxide incorporated solid-state hybrid silica gel glasses and their improved nonlinear optical response

Solid-state graphene oxide (GO) homogeneously incorporated silica gel glasses have been successfully fabricated, and the good nonlinear optical (NLO) response shown indicates its high potential as the optical limiting material to protect optical detectors and human eyes from damage caused by high power lasers. The GO sheets are covalently functionalized with 3- aminopropyltriethoxysilane and connected to the silica glass matrix through Si-O bonding, resulting in an increase in GO incorporation concentration up to 20.2 mol % (C/SiO2) without reaching the saturation limit. Digital images and element mapping analysis of carbon have confirmed the homogeneous dispersion of GO in the silica gel glass. Because of the higher two-photon absorption coefficient, lower NLO starting threshold, and optical limiting threshold shown at 532 nm wavelength, the NLO performance at this wavelength is better than at 1064 nm. At an input fluence as low as 1.3 J cm-2at 532 nm and 2.3 J cm-2at 1064 nm, the glass incorporated with 5.1 mol % GO starts to exhibit an NLO response, suggesting its potential as a laser optical limiting absorber. In addition to the discussion of the probable reasons behind the phenomenon, it has been demonstrated for the first time that the NLO performance of GO in solid-state silica gel glass is stronger than in deionized water.