Application of Plasmon Resonances to Surface Enhanced Raman Scattering (SERS), Heat-Assisted Magnetic Recording (HAMR), and All-Optical Magnetic Recording
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In this work, we perform the analytical and numerical analyses of the plasmon modes in different metallic nanostructures for the applications to surface-enhanced Raman scattering (SERS), heat-assisted magnetic recording (HAMR) and all-optical magnetic recording. We start with the introduction of physical origin of plasmon resonances in nanoparticles and the eigenmode analysis technique adopted throughout this work in Chap. 1. The excitation of the plasmon modes in nanoparticles subject to optical radiation is also presented. In Chap. 2, we study the dispersion in the SERS enhancement factors with silver nanocube dimers. We perform the mode analysis and calculated the resonance wavelengths of the dipolar plasmon modes in silver nanocube dimers with different configurations. The results show that the SERS enhancement factors are related to the resonance frequencies of the dimers, which are determined by their gap distances and orientations. In Chap. 3, we analytically derive the formula for the computation of resonance permittivities of plasmon modes in spheroidal nanoshells. The dipolar plasmon modes in spheroidal nanoshells possess rotational symmetry which preserves the helicity of circularly polarized light, and consequently, they are useful in all-optical magnetic recording. We have also derived the formulas which indicate how the dipolar plasmon modes in ellipsoidal nanoshells can be excited by uniformly incident field. Light intensities of the optical spots generated by the circularly polarized plasmon modes in spherical nanoshells are computed and compared with those generated by circularly polarized plasmon modes in spheroidal nanoshells. In Chap. 4, we study the plasmon resonances in T-shaped aperture metallic nanofilms and lollipop metallic nanodisks placed nearby different dielectric substrates used in heat-assisted magnetic recording. We developed a constrained eigenvalue problem for specific coupled boundary integral equations to take into account the effect of the surrounding finite dielectric objects. By solving this problem, the resonance frequencies of such metallic nanostructures as well as the corresponding plasmon modes can be computed. The effect of heat sink layers on the plasmon resonances is also discussed. Finally, in Chap. 5, we study the radiation corrections of plasmon resonances in nanoparticles. The red-shifts in resonance frequencies of dipolar plasmon modes with nanocube size are computed and compared with experimental measurement. The results suggest that different dipolar modes have different sensitivities to the rounding of the cube corners and edges.