AdjusTable 3D Plasmonic Archimedes Spiral Lens for Optical Manipulation

A novel adjustable three-dimensional plasmonic Archimedes spiral lens (3D PASL) has been investigated and analyzed in detail by numerical simulations. The 3D PASL consists of a spiraling Archimedes helix slot that is engraved on the inner wall of a funnel-shaped gold film on a silicon dioxide substrate. When the incident light from the bottom of substrate is composed of left-hand circularly polarized (LCP) waves, the transmitted light field will converge completely to a focused point that floats in the hollow funnel. This light field will change into an optical vortex when the incident light is changed to right-hand circularly polarized (RCP) waves. The performance of our 3D PASL is discussed for particle trapping or rotation applications. In addition, the position of the optical focus or vortex can be adjusted by varying the height of the structure. Our 3D PASL is highly flexible for practical optical manipulation applications and overcomes the problem where the previous two-dimensional PASL could only manipulate particles on the surface.