Plasmonic Spectral Properties of Silver Nanoparticles Based 1D Composite Array
ZHANG Qin-xiu1, 2, WANG Peng-fei1, ZHANG Yue1, 2, WANG Ting1, 2, WANG Wei1, 2, XIONG Tao1, 2, SUN Cheng1, 2*
1. College of Physical Science and Technology, Dalian University, Dalian 116622, China
2. Liaoning Engineering Laboratory of Optoelectronic Information Technology, Dalian 116622, China
Abstract：Surface plasmon effects can be induced in nanoparticles of noble metals upon excitation of incident light, in which the light is coupled into free electrons, causing a collective oscillation of free electrons on the metal surface. When the oscillation frequency of free electrons is the same as that of the incident light, surface plasmon resonance may occur. The surface plasmon resonance effect of metal nanoparticles has various applications in many fields, including physics, chemistry, biology, etc. This work proposes a silver nanoparticle-based 1D composite array, and its surface plasmonic properties are investigated via the finite-difference time-domain method. In this structure, SiO2 is used as the substrate, and two silver nanoparticles are placed on the surface of the SiO2 substrate along the y-axis direction to form a 1D composite array with plane wave incident incident incident vertically along the negative z-axis direction. The results show that the surface plasmons of the 1D composite array are effectively excited in the wavelength range of 300~1 200 nm and that two plasmonic resonance peaks are revealed in the light absorption curve. The plasmonic resonances and their associated electromagnetic fields can systematically be tuned by adjusting the structural parameters of the array, including the nanoparticle size, the shape, and the period of the array. In addition, when one silver nanoparticle is fixed, and the size of the other particle is changed, it can be found that the two plasmonic resonance peaks of its absorption curve change differently. Combining the electric field diagrams, the equipartition excitonic resonance correlates to two different electromagnetic modes. By changing the shape of one of the silver nanoparticles, such as a pyramid, sphere, cylinder,orcube, it can be found that when the shape of the nanoparticle changes, the corresponding wavelength of the two plasmonic resonance peaks does not change, but the electromagnetic field distribution generated by different particle shapes is different, and the relative electromagnetic field intensity at the bottom is also significantly different. It can also be verified that the absorption curve has two different electromagnetic field modes. The results indicated in this work are significant in future research on designs of noble metal nanoparticle array-based plasmonic devices.
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