Phase and polarization singularities are important degrees of freedom for electromagnetic field manipulation. Detecting these singularities is essential for modern optics, but it is still a challenge, especially in integrated optical systems. In this paper, we propose an on-chip plasmonic spin-Hall nanograting structure that simultaneously detects both the polarization and phase singularities of the incident cylindrical vortex vector beam (CVVB). The nanograting is symmetry-breaking with different periods for the upper and lower parts, which enables the unidirectional excitation of the surface plasmon polariton depending on the topological charge of the incident optical vortex beam. Additionally, spin-Hall meta-slits are integrated onto the grating so that the structure has a chiral response for polarization detection. We demonstrate theoretically and experimentally that the designed structure fully discriminates both the topological charges and polarization states of the incident beam simultaneously. The proposed structure has great potential in compact integrated photonic circuits.

Optical technologies have transformed medical diagnostics, surgery, and therapeutics in recent decades and the medical device industry provides vast opportunity for optical technology. Optical fields in medicine account for $73 billion of the global market and include ophthalmic optics, robotics, lasers, optical surgery, microscopy, and endoscopy, making it the largest technology sector in medicine.¹ Given the size of this sector, it is likely that there will be advances in optical fibers, making them thinner and smaller; use of imaging techniques such as optical coherence tomography (OCT) will become more widespread with greater resolution and providing noninvasive imaging; and laser-based therapeutics will become more accurate and widespread.² Optical devices are used by the majority of medical disciplines and do not consist only of microscopes; they range from otoscopes and ophthalmoscopes to endoscopes and colonoscopes, including surgical microscopes and imaging during robotically assisted surgery.

Surface plasmons (SP’s) are electromagnetic surface waves that propagate along the interface between conductors and dielectrics. The k vector of these waves is larger than the free-space wave vector. The importance of SP’s lies in the fact that they are extremely sensitive to small changes in the dielectric properties of substances that are in contact with the conductors. This property means that SP’s have many sensor applications; however, when they are used in microscopic applications the lateral resolution is limited to several micrometers. We discuss how this limit can be overcome by use of defocused high-numerical-aperture liquid-immersion objectives. We also present SP images that demonstrate a resolution comparable with that expected from high-numerical-aperture optical microscopes. Finally, we discuss how ultrahigh-numerical-aperture objectives with numerical apertures greater than 1.5 can be expected to have considerable influence on biological imaging.