Optical nonlinearity of Cu:SrTiO3 composite fabricated by negative ion implantation

Optical nonlinearity and dispersion were studied for Cu nanoparticle composite. Negative Cu− ions with 60 keV were applied for implanting into SrTiO3 at a flux of 10 μA/cm2 up to a total fluence of 1 × 1017 ions/cm2. The steady-state optical spectrum of Cu-implanted SrTiO3 showed a surface plasmon resonance resulting from the formation of nanoparticles. Transient transmission and reflection were measured by the pump–probe method with a femtosecond laser system. Optical nonlinearity originated from Cu:SrTiO3 nanoparticle composite and from SrTiO3 matrix overlap, in measured transient spectra. The nonlinear component of Cu:SrTiO3 composite was extracted from the transient spectra with the difference of time response. Nonlinear dielectric coefficient and dispersion around the surface plasmon resonance were derived from extracted transient spectra. The dispersion was compared with a local electric field factor.