Publications associées à Index ellipsoid

Wandering principal optical axes in van der Waals triclinic materials

Nature is abundant in material platforms with anisotropic permittivities arising from symmetry reduction that feature a variety of extraordinary optical effects. Principal optical axes are essential characteristics for these effects that define light-matte ...

Nature Portfolio2024

van der Waals Materials for Overcoming Fundamental Limitations in Photonic Integrated Circuitry

Arslan Mazitov

With the advance of on-chip nanophotonics, there is a high demand for high-refractive-index and low-loss materials. Currently, this technology is dominated by silicon, but van der Waals (vdW) materials with a high refractive index can offer a very advanced ...

AMER CHEMICAL SOC2023

Nonlinear Inverse Problems in Quantitative Phase Imaging

Thanh-An Michel Pham

The topic of this thesis is the development of new algorithmic reconstruction methods for quantitative phase imaging (QPI). In the past decade, advanced QPI has emerged as a valuable tool to study label-free biological samples and uncover their 3D structur ...

EPFL2022

Advanced Techniques in Optical Diffraction Tomography

Ahmed Bassam Sayed Ayoub Mohamed Emam

In this thesis, we study the 3 challenges described above. First, we study different reconstruction techniques and assess the fidelity of each reconstruction results by means of structured illumination and phase conjugation. By reconstructing the 3D refrac ...

EPFL2022

Particle suitable for the manufacture of an implantable soft tissue engineering material

Philippe Renaud, Thomas Michael Braschler, Amélie Barbara Hildegarde Béduer

The particle (1) is suitable for the manufacture of an implantable soft tissue engineering material and comprises: a three-dimensionally warped and branched sheet (2) where (i) the three-dimensionally warped and branched sheet (2) is made from a biocompati ...

2019

Rapid Performance Optimization Method for Photoelectrodes

Sophia Haussener, Yannick Kenneth Gaudy

We report the development of a rapid method for the performance optimization of photoelectrodes. The method requires as an input incident photon-to-current efficiency (IPCE) measurements of a material at two or more wavelengths, an estimation of the comple ...

2019

Local Structural Heterogeneity and Electromechanical Responses of Ferroelectrics: Learning from Relaxor Ferroelectrics

Dragan Damjanovic

Long-range ordering of dipoles is a key microscopic signature of ferroelectrics. These ordered dipoles form ferroelectric domains, which can be reoriented by electric fields. Relaxor ferroelectrics are a type of ferroelectric where the longrange ordering o ...

2018

Determination and optimization of material parameters of particle-based LaTiO2N photoelectrodes

Sophia Haussener, Ulrich Aschauer, Yannick Kenneth Gaudy

We developed a validated numerical model capable of predicting the photocurrent-voltage characteristics of oxide and oxynitride particle-based photoelectrodes and identifying the critical parameters affecting the performance of those photoelectrodes. We us ...

Royal Society of Chemistry2018

Complex Refractive Indices of Cesium–Formamidinium-Based Mixed-Halide Perovskites with Optical Band Gaps from 1.5 to 1.8 eV

Christophe Ballif, Jérémie Werner, Quentin Thomas Jeangros, Matthias Wolfgang Bräuninger, Gabriel Christmann, Florent Sahli, Arnaud Walter, Sylvain Nicolay, Björn Niesen, Gizem Nogay, Philipp Friedrich Hermann Löper, Chien-Jen Yang, Peter Joseph Fiala

Cesium-formamidinium-based mixed-halide perovskite materials with optical band gaps ranging from 1.5 to 1.8 eV are investigated by variable-angle spectroscopic ellipsometry. The determined complex refractive indices are shown to depend on the fabrication p ...

2018

High-Q surface modes in photonic crystal/iron garnet film heterostructures for sensor applications

Giovanni Dietler, Serguei Sekatski, Pavel Kapralov

A novel type of a plasmonic sensor based on a magnetophotonic plasmonic heterostructure with an ultrahigh-Q resonance is considered. A magnetoplasmonic resonance with an angular width of 0.06A degrees, which corresponds to a Q factor of 700 and is a record ...

Springer Verlag2017

Light Scattering Enhancement at the Absorption Edge in Dewetting Droplets of Cyanine Dyes

Frank Nüesch, Jakob Heier, Florent Alexandre Boudoire

Diffraction properties of thin films of dewetted cyanine dye droplets are investigated and related to the complex refractive index. Strong changes in the index of refraction are often found near the absorption edge of organic dyes. Within a small window of ...

Wiley-V C H Verlag Gmbh2017

Integrated angular tracking and plasmonic membrane surfaces for a point of a care refractive index sensor

Hatice Altug, Harry Heinzelmann, Cenk Ibrahim Özdemir, Marie-Claude Bay

We present an optical system which integrates a plasmonic sensing surface and an angular tracking system to enable a compact refractive index measurement. A refractive index change at the surface of the sensing membrane causes a change in the angle at whic ...

Spie-Int Soc Optical Engineering2016

Contribution of spontaneous polarization and its fluctuations to refraction of light in ferroelectrics

Alexander Tagantsev

The expressions for the spontaneous polar contribution delta n (i) (s) to the principal values of the refractive index due to the quadratic electro-optic effect in ferroelectrics have been considered within the phenomenological approach taking into account ...

Maik Nauka/Interperiodica/Springer2016

Excitation of resonant plasmonic cavities by integrated waveguides for sensing applications

Gaël David Osowiecki

Optical sensors represent a large growing market which is nowadays focusing onto advancement in mobile technology. Innovations in the field of optical sensors are mostly driven by the technological advancements in the domain of micro & nanofabrication. One ...

EPFL2016

Complex Refractive Index Spectra of CH3NH3PbI3 Perovskite Thin Films Determined by Spectroscopic Ellipsometry and Spectrophotometry

Christophe Ballif, Jun Ho Yum, Stefaan De Wolf, Björn Niesen, Soo-Jin Moon, Michael Elias Stückelberger, Jérémie Werner

The complex refractive index (dielectric function) of planar CH3NH3PbI3 thin films at room temperature is investigated by variable angle spectroscopic ellipsometry and spectrophotometry. Knowledge of the complex refractive index is essential for designing ...

Amer Chemical Soc2015

Mid-infrared plasmonic biosensing with graphene

Hatice Altug, Dordaneh Etezadi, Daniel Rodrigo Lopez, Odeta Limaj

Infrared spectroscopy is the technique of choice for chemical identification of biomolecules through their vibrational fingerprints. However, infrared light interacts poorly with nanometric-size molecules. We exploit the unique electro-optical properties o ...

American Association for the Advancement of Science2015

An impedance-based flow microcytometer for single cell morphology discrimination

Philippe Renaud, Ludovica Colella, Marjan Shaker

Cell shape is a fundamental biological feature, providing specific information about physiological or pathological cellular conditions. Most of the state-of-the-art microfluidic cytometers, however, only allow simple cell analysis, including viability stud ...

Royal Soc Chemistry2014

Interaction of a point charge with the surface of a uniaxial dielectric

Primoz Rebernik Ribic

We analyze the force on a point charge moving at relativistic speeds parallel to the surface of a uniaxial dielectric. Two cases are examined: a lossless dielectric with no dispersion and a dielectric with a plasma-type response. The treatment focuses on t ...

IOP Publishing - EPL Association2013

Refractive index sensor based on slot waveguide cavity

Hans Peter Herzig, Qing Tan, Armando Cosentino

The experimental study of a gold slot waveguide cavity is presented. The resonance of this cavity working in the telecom wavelength range is highly dependent on the refractive index of the medium located in or around the slots array, because of the high co ...

European Optical Soc2012

Optical description of solid-state dye-sensitized solar cells. I. Measurement of layer optical properties

Michael Graetzel, Henry Snaith

The efficiency of a photovoltaic device is limited by the portion of solar energy that can be captured. We discuss how to measure the optical properties of the various layers in solid-state dye-sensitized solar cells (SDSC). We use spectroscopic ellipsomet ...

2009