Ion-Beam-Synthesized Colloidal Silver Nanoclusters in Crystalline Sapphire as Third-Order Optical Material

Silver ion implantation in single-crystalline sapphire has given rise to the formation of silver nanoparticle-sapphire composites, which have been imaged using transmission electron microscopy, and confirmed using linear optical absorption and Rutherford backscattering spectrometry. Nonlinear refractive index and two-photon absorption of these nanocomposites have been observed using Z-scan and Anti-resonant Interferometric Nonlinear Spectroscopy (ARINS) in the close proximity of surface plasmon resonance (SPR) wavelength of silver nanoclusters (~400 nm) and at ~807 nm, respectively. Both sign and value of the nonlinear parameters were determined, and the third-order optical susceptibility (χ⁽³⁾) of the composites has been found to be significant. Such metal nanocomposites in glasses and sapphires having appreciable χ⁽³⁾ with temporal responses in picosecond to femtosecond time domain have great relevance to futuristic switching materials in nanophotonics.