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Conference on Lasers and Electro-optics Europe (CLEO EUROPE)

作者： Alessandro Alberucci Chandroth P. Jisha Monika Monika Ulf Peschel Stefan Nolte Friedrich Schiller University Jena Institute of Applied Physics Jena Germany Friedrich Schiller University Jena Institute of Solid State Physics and Optics Jena Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Jena Germany

ISBN: (纸本)9798350345995

Periodic structures along the propagation direction of light yields the very well known Bragg reflection. When the wavelength is away from any Bragg resonance, in first approximation optical beams perceive the average value of the refractive index. This idea is used, for example, in realizing the so called segmented or Bragg waveguides, once the refractive index is free to vary also across the transverse direction. Following this model, light should freely diffract if the average value of the refractive index is uniform across the wavefront, see Fig. 1(a). The above conclusion, even if quite appealing, is factually wrong due to the emergence of an additional phase contribution due to the Kapitza effect: the local transverse gradient induces a modulation of the transverse wave vector; when the longitudinal average of the effective kinetic energy (thus involving the square of the transverse wave vector) is computed, a longitudinally-independent effective potential emerges. In agreement with the physical origin of the Kapitza effect, the potential is proportional to the square of the modulation period and to the square of the transverse derivative of the refractive index. We already experimentally demonstrated the existence of the Kapitza guiding using synthetic lattice in fiber loops [1]. In this contribution we aim to extend the Kapitza confinement to the case of a point-dependent delay applied to the periodic potential, see Fig. 1(b). Physically speaking, a local gradient is now present even if the amplitude of the periodic oscillation does not vary on the transverse direction [2]. The new contribution to the delay can be interpreted as a gauge fie1d [3], [4] due to the local shifting of the propagation coordinate, providing in turn a new term in the Kapitza potential proportional to the square of the delay derivative. We confirmed the existence of this new way to manipulate waves using BPM numerical simulations and experiments in fiber loops using trains of pulses,

关键词： Light beams Light propagation Modulation Numerical simulation Refractive index Transverse effects

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Processing the bulk of silicon using IR ultrashort laser pulses - from waveguides to welding

Processing the bulk of silicon using IR ultrashort laser pul...

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2022 Conference on Lasers and Electro-optics Pacific Rim, CLEO-PR 2022

作者： Nolte, Stefan Alasgarzade, Namig Alberucci, Alessandro Blothe, Markus Jisha, Chandroth P. Li, Qingfeng Matthäus, Gabor Chambonneau, Maxime Friedrich Schiller University Jena Institute of Applied Physics Abbe Center of Photonics Albert-Einstein-Str. 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Center of Excellence in Photonics Albert-Einstein-Str. 7 Jena07745 Germany

We report on processing the bulk of silicon with infrared ultrashort laser pulses. The localized energy deposition and resulting material modifications enable various applications, from the inscription of waveguides t...

ISBN: (纸本)9798350350012

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Optical metasurfaces made by cell projection lithography: Electron beam nanopatterning with high optical quality on large areas

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PhotonicsViews 2022年第5期19卷 28-31页

作者： Hädrich, Mathias Siefke, Thomas Banasch, Michael Zeitner, Uwe D. Vistec Electron Beam GmbH Ilmstrasse 4 Jena07743 Germany Fraunhofer Institute of Applied Optics and Precision Engineering Albert-Einstein-Straβe 7 Jena07745 Germany

Metasurfaces offer promising possibilities for emerging photonic applications like see-through, near-eye displays. Vistec Electron Beam lithography systems with variable shaped beam (VSB) and cell projection (CP) technology provide a flexible solution to generate repetitive structures on large substrates. Excellent pattern fidelity is achieved in a feasible write-time, enabling prototyping or the manufacturing of replication masters. © 2022 Wiley-VCH GmbH.

关键词： Electron beam lithography

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Enhanced surface second harmonic generation in nanolaminates

Enhanced surface second harmonic generation in nanolaminates

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作者： Abtahi, Fatemeh Paul, Pallabi Beer, Sebastian Kuppadakkath, Athira Pakhomov, Anton Szeghalmi, Adriana Nolte, Stefan Setzpfandt, Frank Eilenberger, Falk Friedrich Schiller University Jena Institute of Applied Physics Abbe Center of Photonics Albert-Einstein-Str. 15 Jena07745 Germany Franhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 Jena07745 Germany Max Plank School of Photonics Jena Germany

Second-harmonic generation (SHG) is a second-order nonlinear optical process that is not allowed in media with inversion symmetry. However, due to the broken symmetry at the surface, surface SHG still occurs, but is generally weak. We experimentally investigate the surface SHG in periodic stacks of alternating, subwavelength dielectric layers, which have a large number of surfaces, thus enhancing surface SHG considerably. To this end, multilayer stacks of SiO2/TiO2 were grown by Plasma Enhanced Atomic Layer Deposition (PEALD) on fused silica substrates. With this technique, individual layers of a thickness of less than 2 nm can be fabricated. We experimentally show that under large angles of incidence (> 20 degrees) there is substantial SHG, well beyond the level, which can be observed from simple interfaces. We perform this experiment for samples with different periods and thicknesses of SiO2/TiO2 and our results are in agreement with theoretical calculations. © 2023 Optica Publishing Group.

关键词： Harmonic generation

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Characterisation of a FPGA-based multi-view stereo system with linear measuring arrangement

Characterisation of a FPGA-based multi-view stereo system wi...

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作者： Junger, Christina Fütterer, Richard Rosenberger, Maik Notni, Gunther Ilmenau Germany Fraunhofer Institute for Applied Optics and Precision Engineering Jena Germany

In recent years, stereoscopic image processing algorithms have gained importance for a variety of applications. To capture larger measurement volumes, multiple stereo systems are combined into a multi-view stereo system (MVS). To reduce the amount of data and the data rate, calculation steps close to the sensors are outsourced to field programmable gate arrays (FPGAs) as upstream computing units. In this paper a FPGA-based MVS system with linear camera arrangement and part overlapping field of view is presented. The system consists of four FPGA-based passive stereoscopic systems and a downstream processing unit (Zynq Ultrascale ZU9EG SoC). This synchronizes the pre-processing modules and receives the disparity maps via HDMI. A subsequent computing unit calculates a coherent 3d point cloud. Basic investigation of the system is shown to use this system for road damage detection in the future. © 2021

关键词： Damage detection

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Phase-Shifted Fiber Bragg Gratings via Localized Femtosecond Photo-Treatment

Phase-Shifted Fiber Bragg Gratings via Localized Femtosecond...

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Bragg Gratings, Photosensitivity and Poling in Glass Waveguides and Materials, BGPP 2022

作者： Goebel, Thorsten A. Schmittner, Christian P. Lin, Zhiqiang Krämer, Ria G. Siems, Malte P. Imogore, Timothy O. Richter, Daniel Nolte, S. Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Jena Albert-Einstein-Straße 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Center of Excellence in Photonics Albert-Einstein-Straße 7 Jena07745 Germany

We present the realization of phase-shifted FBGs via post-processing using ultrashort laser pulses. Herein, we study the influence of the initial FBG parameters in combination with different extensions of the post-pro... 详细信息

ISBN: (纸本)9781957171166

关键词： Ultrashort pulses

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Realization of Chirped Volume Bragg Gratings in Fused Silica by Femtosecond Phase Mask Inscription

Realization of Chirped Volume Bragg Gratings in Fused Silica...

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Bragg Gratings, Photosensitivity and Poling in Glass Waveguides and Materials, BGPP 2022

作者： Siems, Malte P. Richter, Daniel Goebel, Thorsten A. Krämer, Ria G. Nolte, Stefan Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Jena Albert-Einstein-Straße 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Center of Excellence in Photonics Albert-Einstein-Straße 7 Jena07745 Germany

We demonstrate the first cVBG in fused silica written with ultrashort laser pulses. First steps towards scaling their size to enable applications such as compact, robust and reliable CPA laser systems are shown. ©... 详细信息

ISBN: (纸本)9781957171166

关键词： Ultrashort pulses

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Investigation on Volume Bragg Gratings in Athermal Glass by Femtosecond Phase Mask Inscription

Investigation on Volume Bragg Gratings in Athermal Glass by ...

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Bragg Gratings, Photosensitivity and Poling in Glass Waveguides and Materials, BGPP 2022

作者： Richter, Daniel Siems, Malte P. Goebel, Thorsten A. Krämer, Ria G. Nolte, S. Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Jena Albert-Einstein-Straße 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Center of Excellence in Photonics Albert-Einstein-Straße 7 Jena07745 Germany

We demonstrate the first reflective VBGs in an athermal glass inscribed by ultrashort laser pulses. Grating properties are investigated and compared with theoretical predictions concerning their insensitivity to ambie... 详细信息

ISBN: (纸本)9781957171166

关键词： Glass

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Photon pairs in 3R-stacked MoS2

Photon pairs in 3R-stacked MoS2

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Frontiers in optics + Laser Science 2023, FiO, LS 203: Part of Frontiers in optics + Laser Science 2023

作者： Weissflog, Maximilian A. Fedotova, Anna Tang, Yilin Laudert, Benjamin Abtahi, Fatemeh Shradha, Sai Shinde, Saniya Saravi, Sina Staude, Isabelle Pertsch, Thomas Lu, Yuerui Setzpfandt, Frank Eilenberger, Falk Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Jena Jena07745 Germany Institute of Solid State Physics Friedrich Schiller University Jena Jena07743 Germany School of Engineering College of Science and Computer Science The Australian National University CanberraACT2601 Australia Institute for Condensed Matter Physics Technical University of Darmstadt Darmstadt64289 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Jena07745 Germany

We demonstrate photon-pair generation through spontaneous parametric downconversion in transition metal dichalcogenides, namely 3R-MoS2. By exciting 278nm thick 3R-MoS2 stacks at 788nm, we produce entangled photon-pai... 详细信息

ISBN: (纸本)9781957171296

关键词： Crystal orientation Diode lasers Femtosecond lasers Parametric down conversion Second harmonic generation Ultrafast lasers

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Characterization of femtosecond laser-written waveguides in silicon

Characterization of femtosecond laser-written waveguides in ...

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Conference on Lasers and Electro-optics (CLEO)

作者： Namig Alasgarzade Alessandro Alberucci Markus Blothe Maxime Chambonneau Chandroth P. Jisha Stefan Nolte Institute of Applied Physics Abbe Center of Photonics Friedrich-Schiller-Universität Jena Jena Germany Center of Excellence in Photonics Fraunhofer Institute for Applied Optics and Precision Engineering IOF Jena Germany

We characterize laser-written waveguides in silicon versus the inscription parameters such as scanning speed and pulse energy. The analysis is carried out at different wavelengths and polarization states. Finally, the... 详细信息

ISBN: (纸本)9781957171258

关键词： Femtosecond pulses Laser sources Material properties Refractive index Silicon Waveguides

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