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

作者： Gili, Valerio Flavio Dupish, Dupish Vega, Andres Gandola, Massimo Manuzzato, Enrico Perenzoni, Matteo Gasparini, Leonardo Pertsch, Thomas Setzpfandt, Frank Friedrich-Schiller-Universität Jena Institute of Applied Physics Abbe Center of Photonics Jena07745 Germany Fondazione Bruno Kessler Trento38123 Italy Fraunhofer Institute for Applied Optics and Precision Engineering Jena07745 Germany

ISBN: (纸本)9798350345995

Ghost Imaging (GI) is a fascinating imaging technique that exploits second-order correlations of light to investigate samples without directly observing them with a camera [1]. Quantum GI (QGI) version exploits correlations stemming from photon pairs generated by spontaneous parametric down-conversion (SPDC) [2]. It retrieves images from two-path correlation measurements, where single-path detection is not sufficient to obtain an image of the target. Since early demonstrations, this technique has suffered in terms of scalability due to the difficulty of efficiently performing spatially resolved single-photon detection. Early demonstrations suffered from detection efficiency limitations, due to raster scanning spatial detection. More recent camera-based experiments relying on intensified CCD cameras obtain only a limited frame rate and need complex image-preserving delay-lines [3]. More recently, SPAD arrays, two-dimensional arrangement of single-photon avalanche detectors, have been developed and employed in a number of quantum imaging and spectroscopy schemes, dramatically improving detection performances [4]. Here we report on a QGI implementation exploiting a 2D SPAD array detector for the spatially resolving path, solving limitations in terms of frame-rate and the need for optical delay lines. Our experiment enables the acquisition of an image in under one minute, and with much higher frame rate compared to the state-of-the-art. We further take advantage of non-degenerate SPDC to interrogate a Si-Au target. While light interaction with the sample happens at infrared wavelengths, no infrared cameras are needed to obtain an image, and spatial detection is performed in the visible region. This two-color scheme allows to make use of the advanced and cost-efficient silicon-technology while still investigating a sample in spectral regions where cameras are too expensive or not yet available [5]. Our findings advance the state-of-the-art of QGI schemes towards practica

关键词： Photons

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Photon-Pair Recombination via Sum-Frequency Generation by Chirped, Aperiodically Poled LiNb Waveguide

Photon-Pair Recombination via Sum-Frequency Generation by Ch...

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

作者： Hendra, Patrick León-Torres, Josué Ricardo Gräfe, Markus Fraunhofer Institute of Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 Jena07745 Germany Abbe Center of Photonics Friedrich-Schiller-Universität Jena Albert-Einstein-Straße 6 Jena07745 Germany Institute of Applied Physics Technical University of Darmstadt Schloßgartenstraße 7 Darmstadt64289 Germany

ISBN: (纸本)9798350345995

In the past couple of decades, the use of quantum states of light has been gaining interest in different disciplines from telecommunications to imaging and sensing due to its non-classical features that allow to exceed classical limitations. A quantum enhancement in fluorescence microscopy has been explored in a recent study, whereby, time-frequency-entangled photon pairs generated through spontaneous parametric down conversion (SPDC) process were used to demonstrate linear absorption rates in standard fluorophores by the virtue of entangled two-photon absorption (ETPA) [1]. Meanwhile, a prior study on sum-frequency generation (SFG) with down-converted photon pairs has demonstrated that the rate of photon pair recombination is linearly proportional to the down-converted bandwidth [2]. In other words, as the bandwidth of the down-converted photon pairs increases, it reduces the temporal separation between the photons, which in turn, increases the probability for up-conversion via SFG. © 2023 IEEE.

关键词： Bandwidth

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Prospects in power scaling of fiber lasers and amplifiers

Prospects in power scaling of fiber lasers and amplifiers

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

作者： Tünnermann, Andreas Institute of Applied Physics Abbe Center of Photonics Friedrich Schiller University Jena Albert-Einstein-Strasse 15 Jena07743 Germany Fraunhofer Institute for Applied Optics and Precision Engineering Albert-Einstein-Strasse 7 Jena07745 Germany

ISBN: (纸本)9798350345995

In the past years rare-earth-doped fiber lasers have emerged as an attractive and power scalable solid-state laser concept due to the outstanding thermo-optical properties of an actively doped fiber. Using advanced fiber designs, in continuous-wave (cw) operation output powers exceeding the 10 kW-level with diffraction-limited beam quality have been demonstrated. In the pulsed regime average powers in the order of several hundred Watt even for few cycle pulses based on fiber lasers have been reported. © 2023 IEEE.

关键词： Fiber lasers

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Mid-Infrared Quantum Scanning Microscopy with Visible Light

Mid-Infrared Quantum Scanning Microscopy with Visible Light

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

作者： León-Torres, Josué Ricardo Fuenzalida, Jorge Gilaberte, Marta Töpfer, Sebastian Gräfe, Markus Fraunhofer Institute of Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 JenaD-07745 Germany Friedrich-Schiller-Universität Jena Abbe Center of Photonics Max-Wien-Platz 1 JenaD-07745 Germany Institute of Applied Physics Technische Universität Darmstadt Schloßgartenstraße 6 DarmstadtD-64289 Germany

ISBN: (纸本)9798350345995

Laser scanning microscopy (LSM) is known to be the workhorse for modern life-science, it allows to get new insights into a variety of biological processes. LSM together with illumination in the mid infrared region (Mid-IR) permits to map the chemical composition of samples to a space frame. However, low-light observations in the Mid-IR spectrum are still challenging and a limiting factor for a faster development. A label-free quantum scanning imaging system is presented here, capable of performing the detection in the visible regime, while the illumination is carried out in the Mid-IR region. Our quantum imaging with undetected light implementation aims to retrieve amplitude and phase images of biological samples containing a variety of functional groups that are present in the Mid-IR region. © 2023 IEEE.

关键词： Infrared devices

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Design and evaluation of miniaturized high numerical aperture and large field-of-view microscope objectives with reduced field curvature 18

Design and evaluation of miniaturized high numerical apertur...

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Endoscopic Microscopy XVIII 2023

作者： Schulz, S.L. Gross, H. Eggeling, C. Messerschmidt, B. GRINTECH GmbH Otto-Eppenstein-Str. 7 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Str. 7 Jena07745 Germany Institute of Applied Optics and Biophysics Friedrich-Schiller-University Jena Max-Wien-Platz 4 Jena07743 Germany Leibniz Institute of Photonic Technology e.V. Albert-Einstein-Str. 9 Jena07745 Germany

ISBN: (纸本)9781510658172

Microbiological imaging in compact and integrated devices allows for a variety of applications such as endomicroscopy or neuroscience. Typically, such devices require a large field-of-view with a high resolution to visualize cellular details and a high light collection efficiency to improve the signal-to-noise ratio and reduce exposure times. Thus, high numerical apertures are required. Miniature objectives with a numerical aperture of 0.7, a field-of-view diameter of 264 µm in the sample plane and color correction for a wide spectral range (450 nm – 900 nm) are offered by the company GRINTECH GmbH. However, while these accept curved sample fields as a degree of freedom, many demanding applications in the area of endo- and point-of-care-microscopy desire a field as flat as possible. In the scope of this work a broad optical design study was conducted to minimize the optical curvature of the object field. After having worked out 16 design approaches, the three best designs were shortlisted and investigated considering optical and mechanical design tolerances. The best as-built design was chosen and prototypes made of 6 lenses were manufactured. The diameter of the mounted objective is 2.2 mm with a total length of 13 mm. The performance of the novel micro system was experimentally evaluated by means of a confocal laser-scanning-microscope. © 2023 SPIE.

关键词： Optical design

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Large-Area Sub-5nm Plasmonic Nanogap Arrays: Advanced Fabrication, Characterization and Applications

Large-Area Sub-5nm Plasmonic Nanogap Arrays: Advanced Fabric...

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

作者： Gour, Jeetendra Beer, Sebastian Paul, Pallabi Alberucci, Alessandro Szeghalmi, Adriana Peschel, Ulf Nolte, Stefan Zeitner, Uwe D. Friedrich Schiller University Jena Institute of Applied Physics Albert Einstein Str. 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Str. 7 Jena07745 Germany Friedrich Schiller University Jena Institute of Solid State Theory and Optics Max-Wien Platz 1 Jena07743 Germany Munich University of Applied Sciences Department of Applied Sciences and Mechatronics Loristr. 19 Jena Munich80335 Germany

ISBN: (纸本)9798350345995

In recent years, there has been a growing interest in the study of plasmonic nanogaps, specifically in understanding the fundamental physics of localized surface plasmon resonances (LSPR) and of their interplay with optically induced electron transitions through these tiny gaps. Accordingly, many efforts have been made in fabricating nanogaps with precise control over their thickness and shape. While there are several established methods to achieve such a delicate task, many of them struggle with achieving sub-5nm resolution, reproducibility, and/or scalability over wide areas [1]. However, recent technological advancements in the atomic layer deposition (ALD) technique have brought us closer to realizing metasurfaces featuring extremely thin nanogaps down to single-nanometer widths and fulfilling all the demanding requirements listed above [2]. © 2023 IEEE.

关键词： Electron transitions

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Spectral broadening of IR filamentation in air for coherent anti-Stokes Raman scattering

Spectral broadening of IR filamentation in air for coherent ...

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International Conference on Ultrafast Phenomena, UP 2022

作者： Zhao, Xiaodong Boden, André Nolte, Stefan Ackermann, Roland Friedrich-Schiller-Universität Jena Institute of Applied Physics Abbe Center of Photonics Albert-Einstein-Straße 15 Jena07745 Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Straße 7 Jena07745 Germany

We investigate the coherent anti-Stokes Raman scattering (CARS) in air generated by the spectral broadening of laser induced filamentation at a pulse duration of ~1 ps and a central wavelength of ~1 µm. © 20... 详细信息

ISBN: (纸本)9781957171074

关键词： Raman scattering

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Evaluation of contactless respiratory rate measurement: Thermography vs. rPPG

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Measurement: Sensors 2025年 38卷

作者： Liao, Wang Zhang, Chen Rosenberger, Maik Notni, Gunther Ilmenau University of Technology Department of Mechanical Engineering Ilmenau Germany Fraunhofer Institute for Applied Optics and Precision Engineering Jena Germany

Respiratory rate (RR) is one of the most pivotal vital signs in the foundational assessment of patients. Its applicability spans a diverse range of healthcare sectors, from the sleep monitoring to the critical care medicine. Non-contact methods using cameras for the RR measurement can avoid discomforts of patients, match hygiene requirements better, and is more suitable for telemedicine and remote monitoring. In this work, based on a multimodal camera system, we conduct comparative study on RR measurement based on thermal signal and remote photoplethysmography (rPPG) signals obtained from multichannel (RGB, 780 nm, 940 nm, thermal) videos. We discuss the quality of RR-related information carried by these two different sources and provide respective methods for RR estimation. Experimental results demonstrate that the rPPG-based method achieved a mean absolute error (MAE) of 3.50 breath per minute (bpm) in our experimental dataset with ground truth RR ranging from 6 bpm to 42 bpm, whereas the method based on thermal signals reached a MAE of 1.21 bpm. Additionally, our method based on thermal signal demonstrated good agreement with polysomnography in a clinical validation in sleep laboratory. © 2024

关键词： Photoplethysmography

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Ultrashort Pulse Written Waveguides in Silicon

Ultrashort Pulse Written Waveguides in Silicon

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

作者： Nolte, Stefan Alasgarzade, Namig Alberucci, Alessandro Blothe, Markus Jisha, Chandroth P. Matthäus, Gabor Chambonneau, Maxime Friedrich Schiller University Jena Institute of Applied Physics Abbe Center of Photonics 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 report on the inscription of waveguides in the bulk of crystalline silicon using infrared ultrashort laser pulses. The waveguides are characterized with respect to their structure, refractive index profile and guid... 详细信息

ISBN: (纸本)9781957171166

关键词： Refractive index

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Laser assisted Powder Bed Fusion of pure Molybdenum using ultrashort laser pulses

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Procedia CIRP 2024年 124卷 65-68页

作者： Hagen P. Kohl Lisa Matthäus Brian Seyfarth Stefan Nolte Institute of Applied Physics Abbe Center of Photonics Friedrich-Schiller-Universität Jena Albert-Einstein-Str. 15 07745 Jena Germany Fraunhofer Institute for Applied Optics and Precision Engineering IOF Albert-Einstein-Str. 7 07745 Jena Germany

Refractory metals are used in applications requiring extreme high temperature resistance, e.g. jet propulsion systems in aerospace applications or for controlling nuclear reactions. However, the traditional manufacturing of these metals is demanding and expensive, especially if fine structures are required. Here, we report on the laser assisted powder bed fusion of pure Molybdenum. The high melting point and thermal conductivity together with high susceptibility to solidification fractures of Molybdenum make it difficult to identify a suitable parameter window for the laser based melting process. Thus, we apply an ultrashort pulse laser system operating at a center wavelength of 1030 nm and a repetition rate of 32 MHz with a pulse width of 270 fs for the additive processing. Using the additional parameter field provided by the pulsed laser source we are able to fabricate thin-walled structures well below 100 µm as well as volumetric parts with a relative density close to 100 %.

关键词： additive manufacturing L-BPF laser assisted powder bed fusion selective laser melting ultrashort laser pulses Molybdenum

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