Polarimetry using classical polarizing components and nanostructured beam splitting surfaces

Abstract

Two methods for generation and analysis of the polarization state of light are studied in this thesis. The first method is based on a traditional bulk design consisting of two active components and 3 passive components in order to optimally generate 4 Stokes vectors, and analyse one complete Stokes vector, respectively. The innovative step reported in this thesis is the combination of a 600-1100 nm 2-Ferroelectric Liquid Crystal (FLC) based system with a supercontinuum laser source tuned by an Acousto-Optic Tunable Filter (AOTF). The system operates as a complete spectroscopic Mueller matrix Ellipsometer for transmission measurements, using a single IngGaAs detector. It shows highly promising results in the 700 to 930 nm range with a sub 2% Mueller matrix element error. Equally good results in the 600 to 700 nm regime may also be possible. The behaviour of the AOTF and the FLCs were studied in terms of switching speed and stability. The source reached a stable state within 2 milliseconds after switching, and was stable with a variation <.2% in the short time regime. The FLCs revealed a tendency to drift a short time after switching, and a stable state was not reached until 0.2 seconds after switching was initiated. The second method for generation and analysis of the polarization state of light is the use of passive beam splitting metasurfaces. I outline the design and production steps for beam splitting surfaces, and report the preliminary results for a manufactured Au/oxide/ Au thin film stack. Production involves the deposition of a multilayered film consisting of two layers of Au with an intermediate layer of SiO2, and thin adhesive layers of Ti. Characterisation of the films is performed using spectroscopic ellipsometry, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), and 3D Optical Profilometry. Important properties such as deposition rate and the resulting surface roughness have been determined, and satisfying optical models for each of the materials and the multilayered film have been constructed. This forms a solid foundation for the production of films which can later be nanostructured into beam splitting surfaces.