Accurate Feeding of Nanoantenna by Singular Optics for Nanoscale Translational and Rotational Displacement Sensing

Addressing subwavelength object and displacement is crucial in optical\nnanometrology. We show in this Letter that nano antennas with subwavelength\nstructures can be addressed precisely by incident beams with singularity. This\naccurate feeding beyond the diffraction limit can lead to dynamic control of\nthe unidirectional scattering in the far field. The combination of polarization\ndiscontinuity of the incoming singular beam, along with the rapid phase\nvariation near the antenna leads to remarkable sensitivity of the far field\nscattering to displacement at deep subwavelength scale. This opens a far field\ndeep subwavelength postion detection method based on the interaction of\nsingular optics with nano antennas.\n