AFM-NSOM Nano-Polarimeter: Wide-ranging sensing device for synchronized scanning

•Enhanced AFM-NSOM system tip as a nanoscale polarimeter.•Incident light's four Stokes parameters and polarization states on the Poincare sphere.•Triple-mode device: AFM (topography), NSOM (photonics), nano-polarization (coding).•Design and simulations using Comsol Multi-Physics software package.•Cross-Examination of Analytical, Numerical and Experimental results. This paper explores the use of an enhanced AFM-NSOM system tip as a nanoscale polarimeter. The tip consists of a tungsten-silicon conical photodetector modified with four differently-shaped subwavelength apertures, which enable the determination of incident light's four Stokes parameters and in turn its polarization state on the Poincaré sphere. The system is mounted on a standard Atomic Force Microscope (AFM) cantilever and can serve as a triple-mode scanning system, with complementary topography scanning, optical data analysis, and polarization state detection. The device was designed and simulated using the Comsol Multi-Physics software package, and initial steps toward fabrication were taken using the application of advanced nanotechnology tools to a commercial AFM probe. After a discussion of the advantages and drawbacks of drilled scanning tips vis-a-vis standard ones, the article presents the simulation and fabrication results of the nano-polarimeter tip. 3D tip model with four rectangle apertures. (a) Schematic top view; (b) simulation top view for an illumination polarized in the x direction. The rectangle with its longer side perpendicular to the direction of polarization transmits the greatest amount of light, whereas the one whose longer side is parallel transmits a minimum. Unit: V/m. (c) Top view of the cylinder model with four rectangles apertures; (d) SEM image of FIB drilling of four rectangle holes on the chip of the probe. [Display omitted]