| Integrated optics and optical imaging are two important realms in information optics, however, their developments are hampered by the diffraction limit. Surface plasmon polaritons (SPPs) are surface electromagnetic waves propagating along the interface between metals and dielectrics, and their intensity decreases exponentially with the distance away from metal surface. SPP can overcome the diffraction limit because its wave vector is much larger than that of light in air, thus it has been regarded as one of the most effective carriers in next-generation nanophotonic integrated circuits. The first part of this work in this dissertation is to design various SPP based novel nanophotonic integrated devices, such as metal heterostructured bending waveguide, ridged metal heterostructure for nanofocusing, broadband slow SPP systems etc, the optical properties of which have been confirmed by numerical simulation methods. On the other hand, metamaterials are artifical periodical structures with "lattice constants" that are much smaller than the response wavelength. They exhibit many dramtic effects on the light propagation that don't exsit in natural materials, such as negative refraction, and they have been tremendously successful in achieving subdiffraction imaging, optical invisibility, and slow light etc. The second part of this work in this dissertation is to adopt metamaterials to achieve far-field subdiffraction imaging. The work of this dissertation is divided in to the following parts:1. SPPs bending waveguide and nanofousingWith regard to metal gap waveguides (MGWs) of same width, the effective refractive index for different metal films is different, we design a hetrowaveguide consisting of two kinds of MGWs to guide SPPs. As SPPs tends to propagate with higher effective refractive index, thus the most light energy in the waveguide is confined in the MGW with higher effective refractive index. By properly choosing the geometric parameters, SPPs spot can be confined to very small size below half of the wavelength. We further employ this metal heterowaveguide to construct a SPP bending waveguide, and numerically demonstrate that SPPs transmission exceeds 90% as the bending radius is equal to zero, implying it may serve as an excellent SPP waveguide connector. The metal heterowaveguide based T-shaped spliter and M-Z interferometer are demonstrated to have good transmission in a nanoscale domain. Based on the same principle, we propose a ridged metal heterostructure for nanofocusing. SPPs mainly propagate in the metal surface with higher effective refractive index, and finally are focused at its tip. The enhancement factor exceeds 1000. In addition, based on this structure we further design array probes to achieve multiple nanofocusing for different spatial positions simultaneously. The proposed structure may find potential applications in high-density optical data storage, near-field optical microscopy, optical nanolithography, and bio-and chemosensing etc.2. SPPs rainbow trapping and releasingn at visible frequenciesConsidering metal-dielectric-air model, the effective refractive index of SPPs increases with dielectric thickness, we design a metal film covered by dielectric gratings of graded thickness. Calculated result shows that the dispersion relation is different for different grating thickness, and the wavelength near the upper bandegde of the dispersive curve red shifts with the grating thickness. At the bandedge of dispersive curve, localization effect occurs and light group velocity reduces. For SPPs of a certain visible wavelength, the group velocity is gradually reduced along the propagation direction and finally SPPs are localized at a specific postion in the structure. Thus SPPs of different excitation wavelengths in the visible domain will be localized at different spatial positions along the metal surface, or in other words, trapped rainbow appears. SPP lifetime reaches about 0.36 ps at 635 nm wavelength. Because of the difficulty in fabricating such dielectric gratings of graded thickness in acutual experiment, we propose a more realizable metals film covered by chirped dielectric gratings with same thickness but graded lattice constant. For different lattice constant, the corresponding wavelength near the upper bandegde of dispersive curve is increased with the lattice constant. Similarily, such a structure can aslo achieve SPPs rainbow trapping. In addition, by using another uniform dielectric grating attached to the bottom of the metal film and real-time tuning the refractive index of the grating, the trapped SPPs can be released in sequence. Such a structure may find potential applications in nanoscale buffers, spectrometers, filters, data processors, and quantum optical memories etc.3. Far-field subdiffraction imaging Since metal tends to have negative electric permittivity and dielectric have positive one in the optical frequency range, the combination of which may result in hyperbolic dispersive dispersion. Therefore, metal-dielectric multilayers can support the propagation of evanescent waves, and gradually convert evanescent waves into propagation waves. We propose a kind of V-shaped metal-dielectric multilayers to resolve two linear sources below half of the wavelength. Through the structure's magnification, the imaing distance on the output surfaces can be much larger than half of the wavelength, thus the magnified images can be directly processed by conventional optical imaging systems. In the case of 90~0 wedge angle, the resolution limit of the system is down to 21 nm. Besides, we design a kind of pyramid-shaped metal-dielectric multilayers for resolving eight point sources (eight points construct a trapezoidal bevel) with subdiffraction separations in three-dimensional domain. Through magnification, the imaging distances between the nearest-neighbor point sources on the output surfaces of the structure are all larger than half of the wavelength. By properly changing the geometrical parameters, we are able to resolve eight point sources with different hexahedron structures.
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