We numerically demonstrate the performance of a plasmonic lens composed of an array of
nanoslits perforated on thin metallic film with slanted cuts on the output surface. Embedding Kerr
nonlinear material in nanoslits is employed to modulate the output beam. A two dimensional
nonlinear-dispersive finite-difference time-domain (2D N-D-FDTD) method is utilized. The performance
parameters of the proposed lens such as focal length, full-width half-maximum, depth of focus and
the efficiency of focusing are investigated. The structure is illuminated by a TM-polarized plane
wave and a Gaussian beam. The effect of the beam waist of the Gaussian beam and the incident light
intensity on the focusing effect is explored. An exact formula is proposed to derive electric field
E from electric flux density D in a Kerr-Dispersive medium. Surface plasmon (SPs) modes and
Fabry-Perot (F-P) resonances are used to explain the physical origin of the light focusing
phenomenon. Focused ion beam milling can be implemented to fabricate the proposed lens. It can find
valuable potential applications in integrated optics and for tuning purposes.
© 2012 Optical Society of Korea
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