Surface plasmon gap waveguide wcich creates stiongly enhanced and confined optical near-field

在利用SPGW设计光电路时，导波的传播常数是最基本、最重要的参数之一。由于金属是介电物体，在光频区具有复介电常数，因此导波在SPGW中的传播常数必然具有复值，即衰减常数和相位常数。实用技术对导波的激发及其在SPGW中的传播特性对SPGW的实验研究具有重要意义。由于积分方程法在纳米光子学的模拟中经常被使用，因此用积分方程法计算传播常数的数值技术也很重要。利用体积积分方程，研究了高斯光束通过i型孔径激发表面等离子激元极化子隙波导（SPGW）中的导波。在实际条件下，研究了PGW中激发的光场。利用最小二乘拟合方法计算了模拟光场的复传播常数。研究了SPGW的传播常数（衰减常数和相位常数）与隙宽和隙深的关系。利用上述结果，对SPGW进行了三维成像仿真，验证了SPGW在实际条件下的高性能。对纳米介质物体的成像模拟表明，探针在照明模式、收集-反射模式和收集模式下的功能符合预期，其分辨率与探针的尖端直径近似对应。在实际条件下，利用孔径和散射探针对NSOM进行了多次三维成像模拟。然而，大多数在NSOM中使用散射探针检测分辨率和尖端半径之间关系的模拟都是在假设探针尖端近似于一个半径等于尖端半径的小而孤立的球形物体的情况下进行的。然而，在实际条件下，入射光不仅被尖端散射，而且额外的散射会降低分辨率。因此，在实际条件下不假设简单的球形探针尖端的NSOM成像模拟仍然很重要。为了确定PGP在实际条件下的特性和性能，本研究在没有这种假设的情况下进行了仿真。少

In the design of optical circuits by using SPGW, one of the most fundamental and important parameters is the propagation constant of guided waves. Since the metals are dielectric objects with complex permittivity in the optical frequency region, the propagation constant of guided waves in the SPGW has complex value inevitably, i.e., attenuation constant and phase constant. The excitation of guided waves by the practical techniques and propagation characteristics of excited guided-waves in SPGW will be important for experimental study of SPGW. Numerical techniques of computation of propagation constants by integral equation method will be also important, because integral equation method are often used in the simulation in nanophotonics.The guided waves in the surface plasmon polariton gap waveguide (SPGW) excited by the Gaussian beam through the I-shaped aperture have been investigated by the three-dimensional simulations using a volume integral equation. Optical fields excited in the S … More PGW are investigated under practical conditions. The complex propagation constants are calculated from the simulated optical fields using the least-squares fitting. The dependence of the propagation constant, i.e., attenuation and phase constants, on the gap-width and on the gap-depth of SPGW is investigated. Using above-mentioned results, the three-dimensional (3D) imaging simulations using the SPGW are performed as an example of the high performance of the SPGW under practical conditions. Simulations of imaging for a nanometric dielectric object demonstrate that the probe functions as expected in illumination mode, collection-reflection mode, and collection mode with resolution approximately correspondent to the tip diameter of the probe.A number of 3D imaging simulations for NSOM using aperture and scattering probes under practical conditions have been reported. However, most simulations examining the relationship between resolution and tip radius in NSOM using a scattering probe have been performed on the assumption that the probe tip is approximated by a small and isolated spherical object with radius equal to the tip radius. However, under practical conditions, incident light is scattered not just by the tip, and the additional scatter degrades the resolution. Imaging simulations of NSOM under practical condition without the assumption of a simple spherical probe tip thus remain important. The simulations were conducted without such an assumption in order to determine the characteristics and performance of the PGP under practical conditions in this research. Less