Diffractive order Mueller matrix ellipsometry for the design and manufacture of polarization beam splitting metasurfaces.

Optical metasurface technology promises an important potential for replacing bulky traditional optical components, in addition to enabling new compact and lightweight metasurface-based devices. Since even subtle imperfections in metasurface design or manufacture strongly affect their performance, there is an urgent need to develop proper and accurate protocols for their characterization, allowing for efficient control of the fabrication. We present non-destructive spectroscopic Mueller matrix ellipsometry in an uncommon off-specular configuration as a powerful tool for the characterization of orthogonal polarization beam-splitters based on a-Si:H nanopillars.

Dispersion of resonant modes in patch antenna lattices.

Spectroscopic polar angle resolved Mueller matrix ellipsometry at multiple azimuthal incidences, together with a full-field model, reveal new details in the interplay between localized gap surface plasmon resonances and propagating surface plasmon polaritons (SPPs) in a rectangular array of metal-insulator-metal patches. A plane-wave expansion of the field in the insulator shows that the fundamental localized resonances are composed of oppositely propagating modes. Sharp dispersive resonances observed in p-polarization, excited near the opening of diffracted orders, are shown to be grating coupled SPPs.

Effects of optical activity to Mueller matrix ellipsometry of composed waveplates.

Mueller matrix ellipsometry has been used to precisely characterize quartz waveplates for demanding applications in the semiconductor industry and high precision polarimetry. We have found this experimental technique to be beneficial to use because it enables us to obtain absolute and precise measurement of retardation in a wide spectral range, waveplate orientation, and compound waveplate adjustment. In this paper, the necessity of including the optical activity in the Mueller matrix model and data treatment is demonstrated.

Dispersion of polarization coupling, localized and collective plasmon modes in a metallic photonic crystal mapped by Mueller Matrix Ellipsometry.

We report a spectroscopic Mueller matrix experimental study of a plasmonic photonic crystal consisting of gold hemispheroidal particles (lateral radius 54 nm, height 25 nm) arranged on a square lattice (lattice constant 210 nm) and supported by a glass substrate. Strong polarization coupling is observed for ultraviolet wavelengths and around the surface plasmon resonance for which the off-block-diagonal Mueller matrix elements show pronounced anisotropies. Due to the Rayleigh anomalies, the block-diagonal Mueller matrix elements produce a direct image of the Brillouin Zone (BZ) boundaries of the lattice and resonances are observed at the M-point in the first and at the X-point in the second BZ.

Combined imaging of oxidative stress and microscopic structure reveals new features in human atherosclerotic plaques.

Human atherosclerotic samples collected by carotid endarterectomy were investigated using electronic paramagnetic resonance imaging (EPRI) for visualization of reactive oxygen species, and nonlinear optical microscopy (NLOM) to study structural features. Regions of strong EPRI signal, indicating a higher concentration of reactive oxygen species and increased inflammation, were found to colocalize with regions dense in cholesterol crystals as revealed by NLOM.

Mueller matrix three-dimensional directional imaging of collagen fibers.

A method for measuring three-dimensional (3-D) direction images of collagen fibers in biological tissue is presented. Images of the 3-D directions are derived from the measured transmission Mueller matrix images (MMIs), acquired at different incidence angles, by taking advantage of the form birefringence of the collagen fibers. The MMIs are decomposed using the recently developed differential decomposition, which is more suited to biological tissue samples than the common polar decomposition method.

Parametric model of the Mueller matrix of a Spectralon white reflectance standard deduced by polar decomposition techniques.

Decomposition methods have been applied to in-plane Mueller matrix ellipsometric scattering data of the Spectralon reflectance standard. Data were measured at the wavelengths 532 nm and 1500 nm, using an achromatic optimal Mueller matrix scatterometer applying a photomultiplier tube and a high gain InGaAs detector for the two wavelengths. A parametric model with physical significance was deduced through analysis of the product decomposed matrices.

Overdetermined broadband spectroscopic Mueller matrix polarimeter designed by genetic algorithms.

This paper reports on the design and implementation of a liquid crystal variable retarder based overdetermined spectroscopic Mueller matrix polarimeter, with parallel processing of all wavelengths. The system was designed using a modified version of a recently developed genetic algorithm [Letnes et al. Opt.

Mueller matrix measurements and modeling pertaining to Spectralon white reflectance standards.

The full Mueller matrix for a Spectralon white reflectance standard was measured in the incidence plane, to obtain the polarization state of the scattered light for different angles of illumination. The experimental setup was a Mueller matrix ellipsometer, by which measurements were performed for scattering angles measured relative to the normal of the Spectralon surface from -90° to 90° sampled at every 2.5° for an illumination wavelength of 532 nm.

Quantitative characterization of articular cartilage using Mueller matrix imaging and multiphoton microscopy.

The collagen meshwork in articular cartilage of chicken knee is characterized using Mueller matrix imaging and multiphoton microscopy. Direction and degree of dispersion of the collagen fibers in the superficial layer are found using a Fourier transform image-analysis technique of the second-harmonic generated image. Mueller matrix images are used to acquire structural data from the intermediate layer of articular cartilage where the collagen fibers are too small to be resolved by optical microscopy, providing a powerful multimodal measurement technique.

Mueller matrix measurements of algae with different shape and size distributions.

The full Mueller matrix was measured to obtain the polarization state of the scattered light for a variety of algae with different shapes, wall compositions, sizes, and refractive indices. The experimental setup was a multiple laser Mueller matrix ellipsometer, by which measurements were performed for scattering angles from 16° to 160° sampled at every second degree for wavelengths of 473 nm and 532 nm. Previously, the polarization of light scattered from microalgae was investigated only for a few species, and the Mueller matrix was found to have little variation between the species.

Real-time in situ Mueller matrix ellipsometry of GaSb nanopillars: observation of anisotropic local alignment.

The formation of GaSb nanopillars by low energy ion sputtering is studied in real-time by spectroscopic Mueller matrix ellipsometry, from the initial formation in the smooth substrate until nanopillars with a height of 200-300 nm are formed. As the nanopillar height increased above 100 nm, coupling between orthogonal polarization modes was observed. Ex situ angle resolved Mueller polarimetry measurements revealed a 180° azimuth rotation symmetry in the off-diagonal Mueller elements, which can be explained by a biaxial material with different dielectric functions εx and εy in a plane parallel to the substrate.

Bidirectional reflectance distribution function of Spectralon white reflectance standard illuminated by incoherent unpolarized and plane-polarized light.

A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence.

Fast and optimal broad-band Stokes/Mueller polarimeter design by the use of a genetic algorithm.

A fast multichannel Stokes/Mueller polarimeter with no mechanically moving parts has been designed to have close to optimal performance from 430-2000 nm by applying a genetic algorithm. Stokes (Mueller) polarimeters are characterized by their ability to analyze the full Stokes (Mueller) vector (matrix) of the incident light (sample). This ability is characterized by the condition number, κ, which directly influences the measurement noise in polarimetric measurements.