Abstract
Since surface plasmon polarition (SPP) waves propagate in the definite dielectric/metal region, the propagation loss is an important issue and related to the optical responses like on-resonance states or coupling frequencies. In visible region, plasmonic material Ag has attracted great attentions because of low absorption loss. However, the losses in Ag are not only attributed to the interband or intraband transitions but also to the surface defects and the impurities. We herein develop a fabrication method called HNO3-assisted polyol reduction method that possesses mass production single-crystalline Ag microplates with the largest lateral size up to 50 μm. The growth mechanism and the improved SPP propagation length are investigated, showing that the concentrations of ethylene glycol (EG), HNO3 dominate the growth of Ag microplates and the SPP propagation length is 2 folded longer than the typical E-gun deposited Ag thin film. Such the ultralarge Ag microplates can serve as the low defected, versatile used, buffer layer free plasmonic platform Furthermore, using HNO3-assisted polyol reduction method can control the lateral size of Ag microplates. The use of relatively small size Ag microplates with 3-5 μm is carried out for sinking the photogenerated electrons in the ZnO/Ag heterostrcuture. The growth of ZnO nanowires on Ag microplates shows that the directly contact and the charge transfer effect are confirmed by TEM and XPS observation. The ZnO/Ag contacts can effectively enhance the photocatalytic activity in photoinduced degradation processes, showing that the kinetic constant for our ZnO/Ag heterostructure possesses 1.35 folds than the pure ZnO nanowires. The figure of merit (FOM) value is used for fairly comparing the ability of photodegradation among other ZnO/Ag heterostructure, revealing that our ZnO/Ag heterostructure has a better performance than others (1.02 × 10-2). In the final part, we use metallic Ag and plasmonic Fishbone (FB) structures to develop two kinds of SPP amplitude modulation (SPPAM). One is the use of angular frequency difference to serve as a modulation signal and beats on 1.66 MHz, showing that beat frequency SPPAM works beyond SPP subwavelength region and can be readout by the oscilloscope construction. The other is the use of changing polarization states frequencies and polarization states that can act as the modulation signals in the ranges of 1-10k Hz, showing that the intensity difference between the left/right-sided FB structures with the modulation signals. Taking the advantages of reducing the power consumption and the channel length, we believe that the compact SPPAMs can be used for miniaturizing the modulators and upgrade the 8/16 coding bits to multi-bits.