On-chip plasmonic spin-Hall nanograting for simultaneously detecting phase and polarization singularities

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 singularities: Detecting the indefinable A device with specially designed nano-sized slits simultaneously detects two indefinable properties in a twisting beam of light. The device, designed by Changjun Min, Xiaocong Yuan, Michael Somekh of China's Shenzhen University and colleagues, detects phase and polarization singularities in a cylindrical vector vortex beam, with applications in information processing and communications. Optical singularities are regions within light waves where parameters like phase and polarization cannot be defined. Scientists need an easy and reliable way to detect them so they can be manipulated for a variety of applications. In Fenget al.'sdevice, a cylindrical vortex beam shines on specially designed nano-gratings, exciting a wave called a surface plasmon polariton. This wave's properties depend on the number of twists and degree of spin in the input beam, enabling detection of its singularities. The device is promising for photonic integrated circuits.