Publications de Toralf Scharf | EPFL Graph Search

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We investigate in real space amplitude and phase distributions of light in photonic nanojets emerging from micrometer-sized dielectric spheres with a high-resolution interference microscope. Strong localization of light and a Gouy phase anomaly are witness ...

The non-diverging feature of the Bessel-kind beam leads to multiple phase anomalies along the optical axis in contrary to the focused Gaussian beam. Here, we analyze the phase distributions using in a longitudinal-differential phase mode of a high-resoluti ...

The optical performance of refractive plano-convex microlenses is mainly related to the quality of their (a)spherical surface. An efficient tolerancing of this surface is a key step towards the manufacturing of high quality microlenses. However, we demonst ...

We present an experimental method to study field structures of highly confined light after interaction with microstructures. A high-resolution interference microscope (HRIM) allows us to measure the three-dimensional (3D) amplitude and phase distributions ...

Far field pattern generation is investigated for thick sinusoidal phase grating under a Gaussian beam illumination to obtain a high field of view. We compare the Fraunhofer approximation with the High-NA propagator and demonstrate that the Fraunhofer appro ...

We report on advanced 3D direct imaging of light fields emerging from a photonic nanojet. We used an interference microscope that allows observation of amplitude and phase at the highest resolution. For the first time cross polarization interferometry is u ...

We introduce a limit for the strength of coupling light into the modes of solar cells. This limit depends on both a cell’s thickness and its modal properties. For a cell with refractive index n and thickness d, we obtain a maximal coupling rate of $2c\sqrt ...

A high-power LED-based illumination system has been developed as a replacement for the mercury arc lamps used in mask-aligner lithography. LEDs are arranged in a grid array and placed in the entrance aperture of individual reflectors. Those reflectors decr ...

We report on the light confinement effect observed in non-ideally shaped (i.e., non-spherical) nanoscale solid immersion lenses (SILs). To investigate this effect, nanostructures of various shapes are fabricated by electron-beam lithography. When completel ...

An array of plano-concave mini-lenses is designed to realize a particular version of Light Field camera known as Plenoptic Camera 1.2. The Delano diagram related to the on-axis optical channel of such a camera is computed to show its retro-focus behavior a ...

We revisit the scaling laws in micro-optical systems to highlight new phenomena arising beyond a conventional optical regime, especially when the size of the system approaches to the operational wavelength. Our goal is to visualize the impact of the scalin ...

Refractive microlenses are nowadays widely used in optical systems. Characterizing their surface is essential to ensure their quality and to optimize their fabrication process. This is realized by optical surface profilers thanks to their vertical resoluti ...

With help of liquid crystal polymers (LCP) a polarization sensitive diffuser has been realized. By using convex microstructures made of LCP and an index matching layer, two distinct functions depending on the orientation of the device and the polarization ...

Miniaturized optical systems show often unconventional responses compare to larger systems of the same design. We investigate such new phenomena using microlenses, and demonstrate characteristics beyond the refraction limit of the micro-optical systems. ...

Certain high power laser applications require thin homogeneous laser lines. In this paper we describe the concept, fabrication and characterization of a 1-D diffuser that generates such a line. The device is based on an array of concave cylinder lenses wit ...

Diffractive optical elements are ultra-thin optical components required for constructing very compact optical 3D sensors. However, the required wide-angle diffractive 2D fan-out gratings have been elusive due to design challenges. Here, we introduce a new ...

The uniformity of large microlens arrays in Fused Silica is governed by the production process. It comprises photolithographic patterning of a spin-coated layer of photoresist on a 200mm wafer with a molten resist reflow process and subsequent dry etching. ...

We report on the application of a silicon micromachined lamellar grating interferometer in a Fourier Transform Infrared (FTIR) spectrometer for the detection of gases in the mid-infrared (MIR) region. The FTIR spectrometer was equipped with MIR optical fib ...

In this paper we experimentally investigate optical interactions between gold nanowires and fs-laser written waveguides in a view of applications for stationary-wave integrated Fourier-transform spectrometers in a movable mirror configuration. For this pur ...

Toralf Scharf

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Gouy phase anomaly in photonic nanojets

Multiple Phase Anomalies in Bessel Beam

Specification of aspherical surfaces used as refractive elements in micro-optical systems

Axial phase measurements of light interacting with microstructures

Simulation of microoptics under inhomogeneous illumination: Sinusoidal Phase Grating under Gaussian Beam Illumination

Amplitude and Phase Fields of Photonic Nanojets

Limit of light coupling strength in solar cells

Spatial coherence properties of an LED-based illumination system for mask-aligner lithography

Light confinement effect of non-spherical nanoscale solid immersion lenses

Plano-concave mini-lens array for plenoptic imaging applications

Scaling effect and its impact on wavelength-scale microlenses

Correction of spherical surface measurements by confocal microscopy

Polarization sensitive diffuser

A metamaterial based on coupled metallic nanoparticles and its band-gap property

Unconventional Optical Responses of Wavelength-scale Microlenses: beyond Refraction Limit

Fabrication and Characterization of 1-D diffusing elements

Inverse design and demonstration of high-performance wide-angle diffractive optical elements

Improvements on the uniformity of large-area microlens arrays in Fused Silica

Gas Detection with a Micro FTIR Spectrometer in the MIR Region

Optical properties of waveguide-coupled nanowires for sub-wavelength detection in microspectrometer applications