Large third-order optical nonlinearity of silver colloids in silica glasses synthesized by ion implantation

Abstract

Silver ion implantations in fused silica glasses have been made to synthesize silver nanocluster–glass composites and a combination of ‘Anti-Resonant Interferometric Nonlinear Spectroscopy (ARINS)’ and ‘Z-scan’ techniques has been employed for the measurement of the third-order optical susceptibility of these nanocomposites. The ARINS technique utilizes the dressing of two unequal-intensity counter-propagating pulsed optical beams with differential nonlinear phases, which occurs upon traversing the sample. This difference in phase manifests itself in the intensity-dependent transmission, measurement of which enables us to extract the values of nonlinear refractive index ( η 2) and nonlinear absorption coefficient ( β), finally yielding the real and imaginary parts of the third-order dielectric susceptibility ( χ (3)). The real and imaginary parts of χ (3) are obtained in the orders of 10 −10 e.s.u for silver nanocluster–glass composites. The present value of χ (3), to our knowledge, is extremely accurate and much more reliable compared to the values previously obtained by other workers for similar silver-glass nanocomposites using only Z-scan technique. Optical nonlinearity has been explained to be due to two-photon absorption in the present nanocomposite glasses and is essentially of electronic origin.