Nano-scale Control over Optical Singularities

Optical Singularities have attracted much interest in past decades, enabling advancements in nano-manipulation, bio-sensing and quantum optics, owing to their ability to carry and transfer angular momentum on the nano-scale. Optical Vortices (OVs), in this respect, are phase singularities useful for many applications, such as particle trapping and manipulation, optical communication and super-resolution. Vectorial OVs also exhibit Polarization singularities, known as the C-points, which have been used in recent years to control emission from quantum emitters. Here, we present continuous nano-scale spatial control over optical singularities on a metal-air interface, by varying the polarization state of the light exciting surface plasmon polaritons through a spiral slit. We demonstrate our method using phase-resolved near-field microscopy. Such control over optical singularities opens up exciting possibilities for light in 2D, ranging from new light-matter interactions on a chip to efficiently controlled nanomotors.