Tunable Nonlinear Optical Response of ITO Films with Au@Ag Bimetallic Nanoparticles

The nonlinear optical (NLO) response of indium tin oxide films covered with Au@Ag colloid layer was characterized by a femtosecond single-beam open aperture (OA) Z-scan technique in this study. As the Au@Ag thickness increased, the transition from saturated absorption (SA) to reverse saturated absorption (RSA) was found in these ITO matrix composites. The nonlinear absorption coefficient for these composite materials can be regulated from -6.85 x 10(-7) m/W to 26.06 x 10(-7) m/W. In addition, this work also characterized the structure, morphology, and other optical properties of the specimen, and the finite-difference time-domain (FDTD) results were consistent with the experimental results. The NLO response of the ITO/Au@Ag composites can be attributed to the phase properties, synergistic competition effect, strong interaction based on the epsilon-near-zero (ENZ) mode, and localized surface plasmon resonance (LSPR) between the indium tin oxide films and Au@Ag.

Automated summary

The nonlinear optical response of indium tin oxide films covered with Au@Ag colloid layer was investigated using a femtosecond single-beam open aperture Z-scan technique. The transition from saturated absorption to reverse saturated absorption was observed as the thickness of Au@Ag increased. The nonlinear absorption coefficient of these composite materials can be adjusted from -6.85 x 10(-7) m/W to 26.06 x 10(-7) m/W. Additionally, the structure, morphology, and other optical properties of the specimen were characterized, and the finite-difference time-domain results were in agreement with the experimental results. The NLO response of the ITO/Au@Ag composites can be attributed to phase properties, synergistic competition effect, epsilon-near-zero mode, and localized surface plasmon resonance between indium tin oxide films and Au@Ag.