Optical properties of bimetallic Au-Cu nanocrystals embedded in glass

Bimetallic gold-copper and gold-copper solid solutions nanocrystals (NCs) with orthorhombic morphologies were successfully embedded in sodium borosilicate glass; these materials were fabricated via a facile and synthetic sol-gel technique. Microstructural investigations demonstrate that the Au-Cu intermetallic nanostructure is generated in the glass host. Z-scan technique was applied to reveal the third-order nonlinear optical properties of the as-obtained glasses at the wavelength of 800   nm. The as-synthesized glasses exhibit similar nonlinear behaviors with reverse saturation absorption effects and self-focusing performances. The third-order nonlinear susceptibility χ (3) values were optimized by tuning the sizes of the Au-Cu NCs. The χ (3) of Au-Cu(1), Au-Cu(2) and Au-Cu(3) measured to be 3.1   ×   10 −12 , 5.4   ×   10 −12 , and 4.4   ×   10 −12   esu for the single-pulse energy of 1   μJ. We have discussed the nonlinear optical mechanism of Au-Cu sodium borosilicate glass that may be due to the quantum confinement effects and surface plasmon resonance effects.