Fig. 1. Design of QE-coupled metasurfaces for SAM-OAM photon emission.
(A) Schematic of QE-coupled metasurfaces generating single-mode SAM-OAM photon emission with different topological charges: lR = 0, 1, and 2. The ND-NVs are surrounded by DONRs aligned along the OAM-corresponding trajectories. Insets: Angular view scanning electron microscopy (SEM) image of the central part of the fabricated metasurface along with the ND-NV schematic. Scale bar, 500 nm. (B) Illustration of SAM generation by DONR outcoupling of the QE-excited SPP wave. An individual DONR consists of two orthogonal nanorods with the width (w) = 100 nm, length (l) = 400 nm, and height (h) = 150 nm. (C) Intensity ratio of RCP and LCP components (left axis) and Stokes parameter S3 (right axis) as a function of the nanorod separation d calculated at the radiation wavelength of 670 nm by considering the outcoupling of a plane SPP wave incident on a rectangular (7 μm by 6 μm) periodic array composed of DONRs. (D) Three-dimensional (3D) representation of the superimposed far-field intensity and polarization distribution of the outcoupled beam produced by the rectangular DONR array with the optimized in (C) nanorod separation. The color indicates the value of Stokes parameter S3. a.u., arbitrary units.