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Toralf Scharf

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Related publications (107)

Surface micro-structuring of glassy carbon for precision glass molding of diffractive optical elements

Hans Peter Herzig, Toralf Scharf, Karin Prater

Glassy carbon is used nowadays for a variety of applications because of its mechanical strength, thermal stability and non-sticking adhesion properties. This makes it also a suitable candidate as mold material for precision compression molding of low and h ...

Spie-Int Soc Optical Engineering2014

Shaping intensity behind amplitude masks for proximity correction lithography: Design, measurement and realization

Hans Peter Herzig, David Nguyen, Qing Tan, Toralf Scharf, Krishnaparvathy Puthankovilakam

Proximity exposure techniques in lithography are getting more and more popular because of the cost of ownership advantage of mask aligners compared to projection systems. In this paper a gap between simulation and the final result, the prints will be close ...

Spie-Int Soc Optical Engineering2014

On-chip near-infrared optical spectrometer based on single-mode Epo waveguide and gold nanoantennas

Irène Antoinette Philipoussis, Toralf Scharf, Joab Di Francesco, Maurine Malak Karam Awadallah

We report about optical spectrometry using gold nanostructures printed on top of an integrated optical waveguide. The optical waveguide is a single-mode buried waveguide made from a combination of photo-polymerizable materials and is fabricated by photolit ...

Spie-Soc Photo-Optical Instrumentation Engineers2014

Polymer based single mode optical waveguide for spectroscopy applications

Hans Peter Herzig, Irène Antoinette Philipoussis, Toralf Scharf, Maurine Malak Karam Awadallah

In this work, we present for the first time, two dimensional low loss single mode optical waveguides fabricated with EPO materials. The waveguide geometry has a rectangular shape and it is buried between two EPOCLAD layers. Its refractive index distributio ...

Spie-Int Soc Optical Engineering2013

Light confinement effect of non-spherical nanoscale solid immersion lenses

Hans Peter Herzig, Gaël David Osowiecki, David Nguyen, Myun Sik Kim, Toralf Scharf

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 ...

Spie-Int Soc Optical Engineering2013

Phase anomalies in Talbot light carpets of selfimages

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

An interesting feature of light fields is a phase anomaly, which occurs on the optical axis when light is converging as in a focal spot. Since in Talbot images the light is periodically confined in both transverse and axial directions, it remains an open q ...

Optical Society of America2013

Experimental and theoretical investigation on the misalignment tolerance of a micron-sized solid immersion lens tolerance of a micron-sized solid immersion lens

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

We report an experimental and theoretical study on the alignment error tolerance of a 2 µm-size solid immersion lens (SIL) illuminated by different types of focused spots. Tightly confined focal spots are of great interest for improving the performance of ...

Iop Publishing Ltd2013

A Self-Organized Anisotropic Liquid-Crystal Plasmonic Metamaterial

Toralf Scharf, Feng Liu

A composite material that leads to self organization of mesogen-coated gold nanospheres is synthesized and shows enhanced anisotropic optical properties due to synergistic effects of the mesogens intrinsic birefringence and its ability to drive the self-as ...

Wiley-Blackwell2013

Multiple Phase Anomalies in Bessel Beam

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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 ...

2013

Limit of light coupling strength in solar cells

Christophe Ballif, Hans Peter Herzig, Toralf Scharf, Franz-Josef Haug, Ali Naqavi

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 ...

American Institute of Physics2013

A self-assembled three-dimensional cloak in the visible

Mohamed Farhat, Alastair Cunningham, Toralf Scharf

An invisibility cloak has been designed, realized and characterized. The cloak hides free-standing sub-wavelength three-dimensional objects at the short wavelength edge of the visible spectrum. By a bottom-up approach the cloak was self-assembled around th ...

Nature Publishing Group2013

Phase Anomalies in Micro-Optics

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

We present a comprehensive review on the latest research activities that explore the Gouy phase and indicate the recent experimental progresses for its observations in studies that rely on a longitudinal-differential interferometer. The latter is a far-fie ...

Elsevier, Amsterdam2013

Realization and Characterization of POLICRYPS-like Structures Including Metallic Subentities

Luciano De Sio, Toralf Scharf

A first characterization of newly realized micro periodic structures including metallic nanoparticles is reported. The original mixture, generally utilized for the realization of polymer-liquid-crystal-polymer-slices gratings (POLICRYPS), has been enriched ...

2012

A bottom-up approach to fabricate optical metamaterials by self-assembled metallic nanoparticles

Toralf Scharf

We introduce a novel bottom-up approach to fabricate by self assembly a metamaterial from metallic nanoparticles in a two-step process. In the first step, a metamaterial made of densely packed silver nanoparticles is required. The material dispersion with ...

2012

Phase anomalies in Bessel-Gauss beams

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

Bessel-Gauss beams are known as non-diffracting beams. They can be obtained by focusing an annularly shaped collimated laser beam. Here, we report for the first time on the direct measurement of the phase evolution of such beams by relying on longitudinal- ...

Optical Society of America2012

Axial phase measurements of light interacting with microstructures

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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 ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2012

Generation of highly confined optical bottle beams by exploiting the photonic nanojet effect

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

We report on the generation of photonic nanojets, which resemble optical bottle beams. They are realized by manipulating the illumination of dielectric microspheres. As illumination we use the outer region of deliberately truncated Bessel-Gauss beam or a f ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2012

Observation of Axial Phase Evolution of Highly Confined Light Fields

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

Highly confined light fields demonstrate peculiar phase features, e.g., Gouy phase anomaly. Longitudinal-differential phase measurements by a high-resolution interference microscope are applied to investigate phase evolutions of confined light fields for p ...

2011

Gouy phase anomaly in photonic nanojets

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

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 ...

American Institute of Physics2011

Engineering photonic nanojets

Hans Peter Herzig, Myun Sik Kim, Toralf Scharf

Photonic Nanojets are highly localized wave fields emerging directly behind dielectric microspheres; if suitably illuminated. In this contribution we reveal how different illumination conditions can be used to engineer the photonic Nanojets by measuring th ...

Optical Society of America2011

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