Focusing properties of a novel plasmonic lens allowing for circularly polarized illumination

摘要

We propose a novel plasmonic lens (PLs) that is composed of a gold film with an annular array of nanoholes surrounded by two concentric grooves. The proposed PLs has the advantages of enabling the illumination of a circularly polarized light. Through numerical calculation and analysis, the relationship between the groove positions and the phase difference between the light radiating from the grooves and nanoholes is determined. The finite-difference time-domain method is used to compute the light field and confirms that the proposed PLs can achieve super-resolution, long depth of focus and strong central axisymmetric focusing. The PLs arrays are also studied; it is found that owing to the focusing interaction of the adjacent plasmonic lenses, the focusing performance could be further improved. Our study helps design the easy-to-fabricate PLs and facilitates applications of plasmonic devices.