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Periodic negative refractive index materials based on thin-film structure

Author: WangYan
Tutor: YeYongHong
School: Nanjing Normal University
Course: Optical Engineering
Keywords: Negative refractive index Metamaterial Surface plasmon resonance Babinet principle
CLC: O484.41
Type: Master's thesis
Year: 2011
Downloads: 97
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Abstract

On entering one medium from the other medium, incident light and reflected light were on two sides of the normal line. However, negative refractive metamaterial might produce negative refraction-reflected light on same side of the normal line. The negative refractive metamaterial revealed unique physical properties, and could be applied in any fields.There were many methods to achieve negative refractive index(NRI), and the metal-dielectric-metal (MDM) sandwiched structures periodically perforated wiih aperture arrays was applied in electromagnetic field widely, due to of its small consumption, less consumables and easy integration and production.By both fabricating and simulating MDM metamaterials, we found the geometry size and the lattice structre of the dipole aperture could tune the negative electromagnetic response. To explore the mechanisms of extraordinary optical transmission (EOT) and NRI, we studied the surface plasmon polariton resonance effected by apertures. Moreover, we fabricated complementary structures of MDM metamaterial——metallic array structures to study the availability of Babinet principle in midinfrared frequency. The NRI of the metallic nanoparticle array structures were also studied.The main contents of the thesis are described as follows:We observed the extraordinary optical transmission directly in the transmission spectrum of the sandwiched structures periodically perforated with aperture arrays in midinfrared frequency. By simulating, we retrieved effective electromagnetic parameters of the metamaterials,and found some structures displayed the NRI and others did not. The bandwidth of negative index, magnetic resonance, and electric resonance could be tuned by the aperture length. And a stronger magnetic resonance corresponds to a broader negative-index band. While the aperture length increased, a better FOM could be obtained.In the result of parameters retrieval, not all the structures displayed the NRI. We varied the relative positions among the internal, external SPP resonances, and the localized resonances by changing lattice structure of the aperture arrays, and studied the effects of the relative position of the resonances on EOT and NRI. We found that EOT and NRI were not two independent phenomena and if the internal SPP resonance occurs below the external SPP resonance, a NRI is achieved near the internal SPP resonance.Babinet principle had been applied for many years by the microwave community. However, its application in the optical domain needed more careful consideration. As the MDM metamaterials had great electromagnetic response in midinfrared frequency, we fabricated complementary structures to study the availability of Babinet principle in midinfrared frequency. Moreover, we simulated the metallic MDM array structures.

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