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laser-induced plasma formation in water with up to 400 mJ double-pulse LIBS

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Plasma Science and Technology 2024年第1期26卷 93-100页

作者： Marion HeNKeL Michelle SIeMeNS Ralf MeTHLING Benjamin eMDe Jörg HeRMSDORF Steffen FRANKe Diego GONZALeZ Leibniz Institute for Plasma Science and Technology(INP) Felix-Hausdorff-Straße 2Greifswald 17489Germany laser zentrum hannover e.v.(LZH) Hollerithallee 8Hannover 30419Germany

Double-pulse LIBS is a promising technique for deep-sea *** measurements in shallow water with up to 400 mJ each pulse were done to select laser parameters which promote optimized spectral line emission from plasma even at elevated pressures,where line broadening until loss of most of the spectral information can *** emission spectroscopy,using a Czerny-Turner spectrometer,has been applied to investigate the dependence of the emitted radiation on laser parameters and hydrostatic *** has been found,that higher laser pulse energies,especially with short pulse delay as required in high water pressure,can also have an adverse effect on the measured spectrum.

关键词： double-pulse LIBS underwater plasma formation emission spectrosocpy

Spatial separation effects in a guiding procedure in a modified ion-beam-sputtering process

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Light(Science & Applications) 2015年第1期4卷 109-116页

作者： Sina Malobabic Marco Jupé Detlev Ristau laser zentrum hannover e.v. Hollerithallee 8D-30419 HannoverGermany QUeST:Centre for Quantum engineering and Space-Time Research Leibniz Universität HannoverHannoverGermany

In the present state of the art,ion beam sputtering is used to produce low-loss dielectric *** the manufacturing of a dielectric layer stack,the deposition material must be changed,which requires rapid mechanical movement of vacuum *** mechanical components can be regarded as a risk factor for contamination during the coating process,which limits the quality of high-end laser *** minimize the particle contamination,we present a novel deposition concept that does not require movable components to change the coating material during the coating process.A magnetic field guiding technique has been developed,which enables the tuning of the refractive index in the layer structure by sputtering mixtures with varying compositions of two materials using a single-ion *** versatility of this new concept is demonstrated for a highreflection mirror.

关键词： eM field separation ion beam sputtering plasma guiding

Uv-LeD projection photolithography for high-resolution functional photonic components

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Microsystems & Nanoengineering 2021年第4期7卷 149-159页

作者： Lei Zheng Urs Zywietz Tobias Birr Martin Duderstadt Ludger Overrmeyer Bernhard Roth Carsten Reinhardt hannover Centre for Optical Technologies Leibniz University HannoverHannoverLower Saxony 30167Germany Cluster of excellence PhoenixD(Photonics Opticsand Engineering-Innovation Across Disciplines)HannoverLower Saxony 30167Germany laser zentrum hannover e.v HannoverLower Saxony 30167Germany Institute of Transport and Automation Technology Leibniz University HannoverGarbsenLower Saxony 30823Germany Bremen University of Applied Science BremenBremen 28199Germany

The advancement of micro-and nanostructuring techniques in optics is driven by the demand for continuous miniaturization and the high geometrical accuracy of photonic devices and integrated ***,Uv-LeD projection photolithography is demonstrated as a simple and low-cost approach for rapid generation of two-dimensional optical micro-and nanostructures with high resolution and accuracy using standard optics *** developed system enables the projection of structure patterns onto a substrate with 1000-fold *** devices,e.g.,waveguides and microring resonators,on rigid or flexible substrates with varied geometrical complexity and overall structure dimensions from the nanometer to centimeter scale were successfully *** particular,high-resolution gratings with feature sizes down to 150 nm and periods as small as 400 nm were realized for the first time by this *** made of doped laser active materials were fabricated,and their spontaneous emission was *** demonstrated superior performance of the developed approach may find wide applications in photonics,plasmonics,and optical materials science,among others.

关键词： projection resolution optics

Advanced control and modeling of deposition processes

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Chinese Optics Letters 2013年第13期11卷 30-35页

作者： Detlev Ristau Henrik ehlers Centre of Quantum engineering and Space-Time Research Hannover Germany Department of laser Components Laser Zentrum Hannover e.V. Hannover Germany

During the last decade, striking improvements could be achieved for the precise control of deposition processes in optical coating technology. For example, as a consequence of enormous progresses in measure- ment and computer technology, direct optical monitoring in a broad spectral range can be considered as a common tool in many production e.vironments nowadays. Besides the development of the corresponding hardware and measurement channels, advanced approaches for the evaluation of the acquired data and new multiple sensor monitoring strategies moved into the focus of modern research on the way towards de- terministic deposition techniques. In this context, also innovative concepts for the simulation of deposition processes to forecast the result for a specified coating design and automatic online correction algorithms gained of importance to reduce the risk of failure in coating production. The present contribution will be dedicated to selected aspects in this field, especially addressing broad band optical monitoring systems. A short review on examples for existing hardware configurations and software tools will be presented illus- trating the advantages of modern process control techniques. Novel approaches based on the modeling of thin film growth are discussed as an additional strategy to improve the predictability of coating processes.

关键词： 310.1860 Deposition and fabrication 310.6845 Thin film devices and applications 280.4788 Optical sensing and sensors

Spatial heterogeneity of flesh-cell osmotic potential in sweet cherry affects partitioning of absorbed water

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Horticulture Research 2020年第1期7卷 2104-2113页

作者： eckhard Grimm Daniel Pflugfelder Jan Hahn Moritz Jonathan Schmidt Hendrik Dieckmann Moritz Knoche Institut für Gartenbauliche Produktionssysteme Leibniz Universität HannoverAbteilung ObstbauHerrenhäuser Straße 2D-30419 HannoverGermany Forschungszentrum Jülich IBG-2:PflanzenwissenschaftenWilhelm-Johnen-StraßeD-52428 JülichGermany laser zentrum hannover e.v. Hollerithallee 8D-30419 HannoverGermany

A fleshy fruit is commonly assumed to resemble a thin-walled pressure.vessel containing a homogenous carbohydrate *** sweet cherry(Prunus avium L.)as a model system,we investigate how local differences in cell water potential affect H2O and D2O(he.vy water)*** partitioning of H2O and D2O was mapped nondestructively using magnetic resonance imaging(MRI).The change in size of mesocarp cells due to water movement was monitored by optical coherence tomography(OCT,non-destructive).Osmotic potential was mapped using microosmometry(destructive).virtual sections through the fruit revealed that the H2O distribution followed a net pattern in the outer mesocarp and a radial pattern in the inner *** patterns align with the disposition of the.vascular bundles.D2O uptake through the skin paralleled the acropetal gradient in cell osmotic potential gradient(from less negative to more negative).Cells in the.vicinity of a vascular bundle were of more negative osmotic potential than cells more distant from a vascular *** revealed net H2O uptake was the result of some cells loosing volume and other cells increasing volume.H2O and D2O partitioning following uptake is non-uniform and related to the spatial heterogeneity in the osmotic potential of mesocarp cells.

关键词： potential Spatial bundle

Waterproof coatings for high-power laser cavities

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Light(Science & Applications) 2019年第1期8卷 1063-1068页

作者： Xinbin Cheng Siyu Dong Song Zhi Sebastian Paschel Istvan Balasa Detlev Ristau Zhanshan Wang MOe Key Laboratory of Advanced Micro-Structured Materials Shanghai 200092China Institute of Precision Optical engineering School of Physics Science and EngineeringTongji UniversityShanghai 200092China IFSA Collaborative Innovation Center Shanghai Jiao Tong UniversityShanghai 200240China laser zentrum hannover e.v. Laser Components DepartmentHannover 30419Germany

With the ever-increasing laser power and repetition rate,thermal control of laser media is becoming increasingly *** for widely used air cooling or a bonded heat sink,water cooling of a laser medium is more effective in removing waste ***,how to protect deliquescent laser media from water erosion is a challenging ***,novel waterproof coatings were proposed to shield Nd:Glass from water *** clarifying the dependence of the waterproof property of single layers on their microstructures and pore characteristics,nanocomposites that dope SiO_(2) in HfO_(2) were synthesized using an ion-assisted co-evaporation process to solve the issue of a lack of a highindex material that simultaneously has a dense amorphous microstructure and wide ***_(0.7)Si_(0.3)O_(2)/SiO_(2) multifunctional coatings were finally shown to possess an excellent waterproof property,high laser-induced damage threshold(LIDT)and good spectral performance,which can be used as the enabling components for thermal control in high-power laser cavities.

关键词： power high property

Simple route toward efficient frequency conversion for generation of fully coherent supercontinua in the mid-IR and Uv range

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Light(Science & Applications) 2016年第1期5卷 216-223页

作者： Ihar Babushkin Ayhan Tajalli Hakan Sayinc Uwe Morgner Günter Steinmeyer Ayhan Demircan Institute of Quantum Optics Leibniz Universität Hannover30167 HanoverGermany Max Born Institute(MBI) 12489 BerlinGermany laser zentrum hannover e.v. 30419 HanoverGermany Hanover Centre for Optical Technologies 30167 HanoverGermany

Fiber supercontinua represent light sources of pivotal importance for a wide range of applications,ranging from optical communications to frequency *** spectra encompassing more than three octaves can be produced,the applicability of such spectra is strongly hampered due to coherence degradation during spectral *** pulse parameters at the cutting edge of currently available laser technology,we demonstrate the possibility of strongly coherent supercontinuum *** a fiber with two zero-dispersion wavelengths a higher-order soliton experiences a temporal breakdown,without any compression or splitting behavior,which leads to nearly complete conversion of input solitonic radiation into resonant nonsolitonic radiation in the dispersive wave *** the process is completely deterministic and shows little sensitivity to input noise,the resulting pulses appear to be compressible down to the sub-cycle level and may thus hold a new opportunity for direct generation of attosecond pulses in the.visible to near ultraviolet wavelength range.

关键词： attosecond pulses optical solitons supercontinuum ultrashort pulses

Localized bursting of mesocarp cells triggers catastrophic fruit cracking

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Horticulture Research 2019年第1期6卷 764-773页

作者： eckhard Grimm Jan Hahn Daniel Pflugfelder Moritz Jonathan Schmidt Dagmar van Dusschoten Moritz Knoche Abteilung Obstbau Institut für Gartenbauliche ProduktionssystemeLeibniz Universität HannoverHerrenhäuser Straße 230419 HannoverGermany laser zentrum hannover e.v. Hollerithallee 830419 HannoverGermany IBG-2:Grimm et al.Horticulture Research(2019)6:79 Page 9 of 10 Pflanzenwissenschaften Forschungszentrum JülichWilhelm-Johnen-Straße52428 JülichGermany

The so-called rain-cracking of sweet cherry fruit severely threatens commercial *** obse.vation tells us that cuticular microcracking(invisible)always precedes skin macrocracking(visible).The objective here was to investigate how a macrocrack *** detached sweet cherry fruit in deionized water induces *** fruit in D2O and concurrent magnetic resonance imaging demonstrates that water penetration occurs only(principally)through the microcracks,with nondetectable amounts penetrating the intact *** coherence tomography of detached,whole fruit incubated in deionized water,allowed generation of virtual cross-sections through the zone of a developing *** mesocarp cell volume increased before macrocracks developed but increased at a markedly higher rate *** change in mesocarp cell volume occurred in a control zone distant from the *** water incubation continued,the cell volume in the crack zone decreased,indicating leaking/bursting of individual mesocarp *** incubation continued still longer,the crack propagated between cells both to form a long,deep *** mesocarp cell turgor did not differ significantly before and after incubation between fruit with or without macrocracks;nor between cells within the crack zone and those in a control zone distant from the *** cumulative frequency distribution of the logtransformed turgor pressure of a population of outer mesocarp cells reveals all cell turgor data followed a normal *** results demonstrate that microcracks develop into macrocracks following the.volume increase of a few outer mesocarp cells and is soon accompanied by cell bursting.

关键词： markedly cracking continued

xtraction of internal phase motions in femtosecond soliton molecules using an orbital-angular-momentum-resolved method

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Photonics Research 2020年第10期8卷 1580-1585页

作者： YUWeI ZHAO JNTAO FAN YOUJIAN SONG UWe MORGNeR MINGLIe HU Uitrafast laser Laboratory Key Laboratory of Opto-electronic Information Science and Technology of Mlinistry of EducationSchool of Precision Instruments and Opto-electronics EngineeringTianjin UniversityTianjin 300072China Institut fiur Quanteroptik Leibniz Universitat HannoverWelfengarten 130167 HaninaverGermeny Cluster of excellence PhoenixD(Photonics Opticsand Engineering-rnrnovation Across Disciplines)30167 HannoverGermany laser zentrum hannover e.v Hollerithalice 830419 HannoverGermany

Internal motions in femtosecond soliton molecules provide insight into universal collective dynamics in various nonlinear *** we introduce an orbital-angular-momentum(OAM)-resolved method that maps the relative phase motion within a femtosecond soliton molecule into the rotational movement of the interferometric beam profile of two optical *** this means,long-term relative phase evolutions of doublet and triplet soliton molecules generated in an all-polarization-maintaining mode-locked er-fiber laser are *** simple and practical OAM-resolved method represents a promising way to directly visualize the complex phase dynamics in a diversity of multisoliton structures.

关键词： polarization soliton resolved