Figure 4: (Color online) Schematics for the “on-chip” optical rotation. A dielectric microlens is integrated with (a) a plasmonic quarter waveplate (milled on a metal film) or (b) a plasmonic spiral waveplate (consisting of V-antenna arrays on a transparent substrate). Linearly polarized light is incident from below and focused on top passing through the microlens. Objects can be trapped at the focus and be rotated on a chip.