Optical switching performance of metal nanoparticles fabricated by negative ion implantation

Linear and nonlinear optical properties of Au and Cu nanoparticle composites, fabricated by ion implantation, were studied with evaluation of applicability to all-optical switching device. Negative ions of 60 keV were implanted into amorphous SiO2 at fluxes of about 10 μA/cm2 to a fluence of 1 × 1017 ions/cm2. The surface plasmon resonance of the Au:SiO2 composite was enhanced stronger than that of the Cu:SiO2 composite because of a difference of the local field in nanoparticles. Nonlinear optical constants were evaluated by the Z-scan method with a tunable femtosecond laser system. The nonlinear absorption coefficients exhibited maximal values of −4.9 × 101 m/GW for Cu:SiO2 and −1.3 × 102 m/GW for Au:SiO2 around the surface plasmon resonance. For application of the composites to optical switching by optical bistability, it was estimated that the reflectivity of resonators is >0.94 for the Au:SiO2 composite and that the switching energy was approximately 10 pJ/bit.