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High-speed, high-resolution, and material-specific coherent EUV imaging using a high-order harmonic source

High-speed, high-resolution, and material-specific coherent ...

Compact EUV and X-Ray Light Sources, EUVXRAY 2024 - Part of Optica High-Brightness Sources and Light-Driven Interactions Congress

作者： Eschen, Wilhelm Liu, Chang Penagos, Daniel S.M. Klas, Robert Limpert, Jens Rothhardt, Jan Helmholtz-Institute Jena Fröbelstieg 3 Jena07743 Germany Institute of Applied Physics Abbe Center of Photonics Friedrich-Schiller-University Jena Albert-Einstein-Str. 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering Albert-Einstein-Str. 7 Jena07745 Germany

We present a tabletop coherent imaging system at 13.5 nm driven by an ultrafast 75 W fiber laser, achieving a record imaging-speed of 5 Mpix/h, enabling detailed chemical composition mapping for samples from microbiol... 详细信息

ISBN: (纸本)9781957171357

关键词： Fiber lasers

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Theory of Spontaneous Parametric Down-Conversion in Thin Etalons

Theory of Spontaneous Parametric Down-Conversion in Thin Eta...

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2023 Conference on Lasers and Electro-optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023

作者： Santos, Elkin A. Setzpfandt, Frank Saravi, Sina Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Jena Albert-Einstein-Str. 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering Albert-Einstein-Str. 7 Jena07745 Germany

ISBN: (纸本)9798350345995

The process of spontaneous parametric down-conversion (SPDC) in χ(2)-materials, in which a pump (P) photon of wavelength λP can split into a pair of entangled signal (S) and idler (I) photons of lower energy, is an instrumental tool in optical quantum technologies. Recently, there has been a growing interest in pair generation in sub-wavelength-thin nonlinear crystals [1,2], especially because they are not restricted by the phase-matching condition and exhibit SPDC in a very wide spectral and angular range. This also motivates their use in quantum imaging applications, for pushing the resolution of such schemes to the limit [3,4]. Despite its seemingly simple appearance, there has not yet been a comprehensive theoretical analysis of photon-pair generation in a thin unstructured nonlinear slab. Specifically, a proper theory should embed the Fabry-Pérot type of interferences that the signal and idler photons experience in such a nonlinear etalon during SPDC. © 2023 IEEE.

关键词： Photons

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Inscription and Characterization of Transversely Written Waveguides in Silicon with Picosecond Laser Pulses

Inscription and Characterization of Transversely Written Wav...

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

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

ISBN: (纸本)9798350345995

The possibility to permanently modify transparent materials and inscribe waveguiding structures with ultrashort laser pulses is well established for dielectrics such as glasses. Such a technique discloses a versatile set of applications, ranging from telecommunications to photonic quantum circuits. Attempts to transfer this 3D ultrafast inscription technique to the most important material in the microelectronics industry, silicon, failed so far for a transverse inscription strategy.

关键词： Femtosecond pulses Nanosecond pulses Picosecond pulses Silicon Ultrafast lasers Ultrashort pulses

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Revisiting Pump Light Absorption in Structured Double Clad Fibers

Revisiting Pump Light Absorption in Structured Double Clad F...

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2023 Conference on Lasers and Electro-optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023

作者： Yildiz, Benjamin Häßner, Denny Grobecker, Anja Kuhn, Stefan Haarlammert, Nicoletta Schreiber, Thomas Fraunhofer Institute for Applied Optics and Precision Engineering Albert Einstein-Str. 7 Jena07745 Germany Institute of Applied Physics Abbe Center of Photonics Friedrich-Schiller-University Jena Albert-Einstein-Str. 15 Jena07745 Germany

ISBN: (纸本)9798350345995

For high power fiber amplifiers with excellent beam quality double clad fibers are an essential tool. They consist of a signal core section, which is doped with a laser active medium and typically centered, and a much larger pump core. The signal which is to be amplified is coupled into the signal core and has typically an excellent beam quality already, while the pump core is the guiding structure for the high power, low brightness pump light which is to be absorbed by the signal core. The theoretical maximum absorption therefore correlates with the core doping concentration and the ratio of signal to pump core area. However due to the pump core being a highly multimode waveguide and all the pump modes having different overlap integrals with the absorbing signal core, the real pump absorption can drastically differ from the theoretical maximum. To ensure optimal absorption, extensive research was already done in the field of cladding pump absorption. The outcome of works such as [1, 2] relies on breaking the symmetry in these fibers by either twisting or coiling them and by utilizing differently shaped pump guiding structures to enhance the pump absorption capabilities. © 2023 IEEE.

关键词： Molecular orbitals

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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... 详细信息

关键词： Ultrashort pulses

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Polarization Dependence of Transverse mode Instability in Yb-doped LMA PM Fibers

Polarization Dependence of Transverse mode Instability in Yb...

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2023 Conference on Lasers and Electro-optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2023

作者： Palma-Vega, Gonzalo Häßner, Denny Kuhn, Stefan Nold, Johannes Möller, Friedrich Jauregui, César Tünnermann, Andreas Haarlammert, Nicoletta Schreiber, Thomas Fraunhofer Institute for Applied Optics and Precision Engineering Albert Einstein-Str. 7 Jena07745 Germany Institute of Applied Physics Abbe Center of Photonics Friedrich-Schiller-University Jena Albert-Einstein-Str. 15 Jena07745 Germany

ISBN: (纸本)9798350345995

Power scaling of fiber lasers is hindered by nonlinear and thermal limitations. The most dramatic limiting effect is transverse mode instability (TMI). It manifests as fluctuations between the fundamental mode (FM) of the fiber and a high order mode (HOM). So far there has not been much research of TMI in polarization maintaining (PM) fibers. Simulations in [1] predicted that different input polarization angles can lead to suppression of TMI. Experimentally, it was reported in [2] that rotating the fiber at the splicing point of a PM fiber led to changes on the TMI threshold. Here in this work, we present systematic measurements of the TMI threshold in a PM large mode area (LMA) fiber in dependence on the input linear polarization angle. We demonstrate that TMI can be strongly influenced by detuning the linear polarization of the seed with respect to the slow-axis of the fiber. The experimental setup consisted of a fiber amplifier used in counter-propagating pump configuration, Fig 1. A linearly polarized seed laser centered at 1030nm was amplified in a LMA PM in-house fiber. The fiber had a signal core diameter of 35µm, a pump core diameter of 200µm, and a low NA of 0.036 (without correction of stress). A fiber length of 1.2 m was coiled with a diameter of 27 cm. The complete fiber was water cooled, twists along the fiber were avoided, and the stress rods were aligned horizontally. The fiber was few-mode for both the slow and the fast-axis, thus the fiber supports the propagation of the LP01 and LP11 modes. The pump power was provided by a wavelength stabilized diode at 976nm with a maximum output power of 800W. We characterized the TMI threshold in dependence on the polarization input angle by rotating the polarization input angle with a halfwaveplate (WP1, Fig 1). © 2023 IEEE.

关键词： Polarization-maintaining fiber

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Experimental Demonstration of Gauge Confinement in Point-Wise Shifted Periodic Potentials

Experimental Demonstration of Gauge Confinement in Point-Wis...

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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

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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