Solid‐State Sintering of Glasses with Optical Nonlinearity from Mesoporous Powders

Silica glasses dispersed with Pt nanoparticles and Ag nanoparticles are derived from solid-state sintering of mesoporous silica SBA-15 encapsulated with Pt nanoparticles and Ag nanoparticles, respectively. Using mesoporous powders for sintering is a facile method to lower synthesis temperature for glass making and to efficiently disperse noble metal nanoparticles in silica glass matrix. The included nanoparticles still play their functional roles in impacting on optical properties of the glass products prepared by this novel method. The glass dispersed with Pt nanoparticles exhibits brown color due to the interband electron transition of Pt nanoparticles. The coloring effect of surface plasmon resonance absorption from Ag nanoparticles colors the glass dispersed with Ag nanoparticles with yellow. Open-aperture and closed-aperture Z-scan methods are applied to measure third-order nonlinear absorption and refraction coefficient of the composite glasses, respectively, under femtosecond laser radiation at 880 nm wavelength. The glass dispersed with Pt nanoparticles behaves intense nonlinear absorption comparing with nonlinear refraction in magnitude, which could be attributed to interband electron transition by monophoton absorption of Pt nanoparticles. The glass dispersed with Ag nanoparticles shows stronger nonlinear refraction than saturated absorption. The dominant contribution to third-order optical nonlinearity of silica glass dispersed with Ag nanoparticles is intraband transition of free electrons near the Fermi surface of Ag nanoparticles. This method may have potential applications for fabricating silica glasses dispersed with ultrafine functional particles, which are potentially applicative in the fields of photonics.