Spatial Oscillations of Surface plasmon in metal-dielectric waveguide arrays

• Main Authors: Ruei-ChengShiu, 許瑞成
• Other Authors: Yung-Chiang Lan
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/27527391619969864735

博士 === 國立成功大學 === 光電科學與工程學系 === 101 === This study investigates plasmonic Bloch oscillations (PBOs) in cylindrical metal–dielectric waveguide arrays (MDWAs) by performing numerical simulations and theoretical analyses. Optical conformal mapping is used to transform cylindrical MDWAs into equivalent chirped structures with permittivity and permeability gradients across the waveguide arrays, which is caused by the curvature of the cylindrical waveguide. The PBOs are attributed to the transformed structure. The period of oscillation increases with the wavelength of the incident Gaussian beam.However, the amplitude of oscillation is almost independent of wavelength.Besides, we elucidate plasmonicZener tunneling (PZT) in metal–dielectric waveguide arrays (MDWAs) by using numerical simulations and theoretical analyses. PZT in MDWAs occurs at the waveguide entrance and wherever the beam completes Bloch oscillations, because the bandgap between the first and second bands is minimal at the center of the first Brillouin zone. This feature significantly differs from that of optical Zener tunneling in dielectric waveguide arrays. The dependence of the simulated tunneling rate on the gradient of the relative permittivity of the dielectric layers correlates with the tunneling theory, thus confirming the occurrence of PZT in MDWAs. Finally, this work investigates plasmonic Bloch–Zener oscillation and beam curling in metal–dielectric waveguide arrays (MDWAs) using numerical simulations and theoretical analyses. The beam generated by plasmonicZener tunneling undergoes a plasmonic Bloch oscillation in the second band of MDWAs and becomes curled. Changing the width and the relative-permittivity gradient of the dielectric layers causes this curled beam to move backward, forward, or even unmoved. Increasing thewidth and the relative-permittivity gradient of the dielectric layers increases the rightward displacement and reduces the leftward displacement. The direction of motion of the curled beam is determined by the net longitudinal displacement.