LAUSR

Abstract We report a rotating optical focal field generated by inversely focusing the radiation pattern from a turnstile antenna under a 4Pi focusing system. The turnstile antenna, composed of two mutually perpendicular short dipoles with a quadrature phase offset, is employed to find the required illumination at the pupil plane for creating the rotating field by using a time-reversal holographic methodology. Numerical results demonstrate that the intensity distribution of the created optical focal field exhibits an “8” shape on the focal plane and rotates with radian frequency ω around the optical axis. The angles for the left- and right-hand rotating focal fields are calculated to be – ω t and ω t, respectively. When ω is large enough, the rotating optical focal field with an “8” shape tends to the steady-state perfectly circular spot with nearly pure circular polarization. This rotating optical focal field may suit a variety of potential applications, such as particle revolving, particle acceleration, and near-field scanning optical microscopy.