Near infra-red Mueller matrix imaging system and application to strain imaging

We report on the design and performance of a near infra-red Mueller matrix imaging ellipsometer, and apply the instrument to strain imag- ing in near infra-red transparent solids. Particularly, we show that the instrument can be used to investigate complex strain domains in multi-crystalline silicon wafers.Comment: Submitted to Thin Solid Films, 14 pages, 10 figure

Diffuse-interface model for nanopatterning induced by self-sustained ion etch masking

We construct a simple phenomenological diffuse-interface model for composition-induced nanopatterning during ion sputtering of alloys. In simulations, this model reproduces without difficulties the high-aspect ratio structures and tilted pillars observed in experiments. We investigate the time evolution of the pillar height, both by simulations and by {\it in situ} ellipsometry. The analysis of the simulation results yields a good understanding of the transitions between different growth regimes and supports the role of segregation in the pattern-formation process.Comment: 10 pages, 3 figures; minor revisions with respect to first version; figures nicened; journal ref. adde

Dynamic Response of a fast near infra-red Mueller matrix ellipsometer

The dynamic response of a near infrared Ferroelectric Liquid Crystal based Mueller matrix ellipsometer (NIR FLC-MME) is presented. A time dependent simulation model, using the measured time response of the individual FLCs, is used to describe the measured temporal response. Furthermore, the impulse response of the detector and the pre-amplifier is characterized and included in the simulation model. The measured time-dependent intensity response of the MME is reproduced in simulations, and it is concluded that the switching time of the FLCs is the limiting factor for the Mueller matrix measurement time of the FLC-based MME. Based on measurements and simulations our FLC based NIR-MME system is estimated to operate at the maximum speed of approximately 16 ms per Mueller matrix measurement. The FLC-MME may be operated several times faster, since the switching time of the crystals depends on the individual crystal being switched, and to what state it is switched. As a demonstration, the measured temporal response of the Mueller matrix and the retardance of a thick liquid crystal variable retarder upon changing state is demonstrated.Comment: to be published in Journal of Modern Optics 20 pages, 6 figure

Field Emission Dark Current of Technical Metallic Electrodes

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration a -500 kV, 250 ns FWHM, pulse will be applied in between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgass and must not emit electrons. Ion back bombardment, and dark current will be damageable to the electron source as well as for the low emittance beam. Electrodes of commercially available OFE copper, aluminium, stainless steel, titanium and molybdenum were tested following different procedures including plasma glow discharge cleaning.Comment: 22 pages, 6 tables, 10 figures Vs 2 : graphics more readable, enhanced content Vs 3 : typo correcte

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. This ability is characterized by the condition number, $\kappa$, which directly influences the measurement noise in polarimetric measurements. Due to the spectral dependence of the retardance in birefringent materials, it is not trivial to design a polarimeter using dispersive components. We present here both a method to do this optimization using a genetic algorithm, as well as simulation results. Our results include fast, broad-band polarimeter designs for spectrographic use, based on 2 and 3 Ferroelectric Liquid Crystals, whose material properties are taken from measured values. The results promise to reduce the measurement noise significantly over previous designs, up to a factor of 4.5 for a Mueller polarimeter, in addition to extending the spectral range.Comment: 10 pages, 6 figures, submitted to Optics Expres

Spectroscopic Mueller matrix ellipsometry of a gap surface plasmon array at conical incidences

Spectroscopic Mueller matrix ellipsometry is used to study an array of rectangular Au patches on a SiO2 film backed by optically thick Au. The array supports resonances related to gap surface plasmons and Rayleigh anomalies, and these are mapped out by full rotation of the azimuthal angle of incidence. The finite element method is used to model the system, and it is found that the Ti adhesion layers at SiO2/Au interfaces used in the manufacture process must be included in the model for accurate results. We show how oxidation of the Ti layer beneath the Au patch causes the optical response to drift in time, and we demonstrate an extreme sensitivity of the Mueller matrix to the dimensions of the patch.acceptedVersio

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. The SPPs show strong coupling with localized modes of similar symmetry, while they appear suppressed by modes of dissimilar symmetry.acceptedVersio

Use of 4x4 transfer matrix method in the study of surface magnon polaritons via simulated attenuated total reflection measurements on the antiferromagnetic semiconductor MnF2

The surface magnon polaritons (SMPs) present in thin film antiferromagnet semiconductors can be extremely confined, having most of their energy distributed within the magnetic medium. For extremely thin films these SMPs can therefore be well described using a quasimagnetostatic treatment. In this work Berreman's 4×4 transfer matrix method (TMM) is used to study the SMPs supported by thicker films, beyond the magnetostatic approximation. Focus is placed on the antiferromagnet semiconductor MnF2 for which attenuated total reflection measurements are modeled, probing the hyperbolic dispersion of the medium. The dispersion relations from both the TMM and the analytical quasimagnetostatic approximation are compared. For thicker films, the coupling efficiencies into the SMP energy channels are analyzed as a function of air gap distances. The TMM is used to probe the SMP dispersion for realistic experimental configurations with modifications including type of substrate, film thickness, and crystal axis orientation. Rich phenomena are observed such as strong SMP-waveguide mode coupling and SMPs with negative refraction.publishedVersio

Dielectric function and band gap determination of single crystal CuFeS2 using FTIR-VIS-UV spectroscopic ellipsometry

publishedVersio