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Artykuły w czasopismach na temat "Mid-IR sources"

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Perger, M., J. Moultaka, A. Eckart, T. Viehmann, R. Schödel i K. Muzic. "Compact mid-IR sources east of Galactic Center source IRS5". Astronomy & Astrophysics 478, nr 1 (20.11.2007): 127–35. http://dx.doi.org/10.1051/0004-6361:20078449.

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Mountrichas, G., I. Georgantopoulos, A. Ruiz i G. Kampylis. "Obscuration properties of mid-IR-selected AGN". Monthly Notices of the Royal Astronomical Society 491, nr 2 (4.11.2019): 1727–35. http://dx.doi.org/10.1093/mnras/stz3076.

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ABSTRACT The goal of this work is to study the obscuration properties of mid-infrared (mid-IR)-selected active galactic nuclei (AGN). For that purpose, we use Wide-field Infrared Survey Explorer (WISE) sources in the Stripe 82–XMM area to identify mid-IR AGN candidates, applying the Assef et al. criteria. Stripe 82 has optical photometry ≈2 times deeper than any single-epoch Sloan Digital Sky Survey (SDSS) region. XMM–Newton observations cover ∼26 deg2. Applying the aforementioned criteria, 1946 IR AGN are selected. ${\sim} 78{{\, \rm per\, cent}}$ have SDSS detection, while 1/3 of them are detected in X-rays, at a flux limit of $\rm {\sim} 5 \times 10^{-15}\, erg\, s^{-1}\, cm^{-2}$. Our final sample consists of 507 IR AGN with X-ray detection and optical spectra. Applying a $r-W2 > 6$ colour criterion, we find that the fraction of optically red AGN drop from 43 per cent for those sources with SDSS detection to $23{{\, \rm per\, cent}}$ for sources that also have X-ray detection. X-ray spectral fitting reveals 40 (${\sim} 8{{\, \rm per\, cent}}$) X-ray absorbed AGN ($N_\mathrm{ H} > 10^{22}\,{\rm cm}^{-2}$). Among the X-ray unabsorbed AGN, there are 70 red systems. To further investigate the absorption of these sources, we construct spectral energy distributions (SEDs) for the total IR AGN sample. SED fitting reveals that ${\sim} 20{{\, \rm per\, cent}}$ of the optically red sources have such colours because the galaxy emission is a primary component in the optical part of the SED, even though the AGN emission is not absorbed at these wavelengths. SED fitting also confirms that $12{{\, \rm per\, cent}}$ of the X-ray unabsorbed IR AGN are optically obscured.
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Sanghera, Jas S., L. Brandon Shaw i Ishwar D. Aggarwal. "Chalcogenide Glass-Fiber-Based Mid-IR Sources and Applications". IEEE Journal of Selected Topics in Quantum Electronics 15, nr 1 (styczeń 2009): 114–19. http://dx.doi.org/10.1109/jstqe.2008.2010245.

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Weidmann, Damien, Chad B. Roller, Clive Oppenheimer, Alan Fried i Frank K. Tittel. "Carbon isotopomers measurement using mid-IR tunable laser sources". Isotopes in Environmental and Health Studies 41, nr 4 (grudzień 2005): 293–302. http://dx.doi.org/10.1080/10256010500384325.

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Gonzalez-Solares, Eduardo A., Nicholas A. Walton, Anita M. S. Richards i Jonathan A. Tedds. "Near-IR properties of Spitzer sources". Proceedings of the International Astronomical Union 2, nr 14 (sierpień 2006): 611. http://dx.doi.org/10.1017/s1743921307012094.

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We present an analysis of the near-IR properties of galaxies and quasars detected in the mid-IR by the Spitzer Space Telescope. Using optical photometry from the Wide Field Survey and near-IR fluxes from the First Data Release of the UKIDSS (Dye et al. 2006) survey we carry out a preliminary characterization of the surface density of different samples of galaxies and their clustering properties.
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Lerch, Ph, P. Dumas, T. Schilcher, A. Nadji, A. Luedeke, N. Hubert, L. Cassinari i in. "Assessing noise sources at synchrotron infrared ports". Journal of Synchrotron Radiation 19, nr 1 (25.11.2011): 1–9. http://dx.doi.org/10.1107/s0909049511041884.

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Today, the vast majority of electron storage rings delivering synchrotron radiation for general user operation offer a dedicated infrared port. There is growing interest expressed by various scientific communities to exploit the mid-IR emission in microspectroscopy, as well as the far infrared (also called THz) range for spectroscopy. Compared with a thermal (laboratory-based source), IR synchrotron radiation sources offer enhanced brilliance of about two to three orders of magnitude in the mid-IR energy range, and enhanced flux and brilliance in the far-IR energy range. Synchrotron radiation also has a unique combination of a broad wavelength band together with a well defined time structure. Thermal sources (globar, mercury filament) have excellent stability. Because the sampling rate of a typical IR Fourier-transform spectroscopy experiment is in the kHz range (depending on the bandwidth of the detector), instabilities of various origins present in synchrotron radiation sources play a crucial role. Noise recordings at two different IR ports located at the Swiss Light Source and SOLEIL (France), under conditions relevant to real experiments, are discussed. The lowest electron beam fluctuations detectable in IR spectra have been quantified and are shown to be much smaller than what is routinely recorded by beam-position monitors.
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Persi, Paolo, Mauricio Tapia i Anna Rosa Marenzi. "Mid-IR images of methanol masers and ultracompact HII regions". Proceedings of the International Astronomical Union 2, S237 (sierpień 2006): 462. http://dx.doi.org/10.1017/s1743921307002505.

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Methanol masers and UCHII regions trace massive star formation sites. We have undertaken a mid-IR survey of 17 regions containing methanol masers and UCHIIs in order to locate the young stellar sources associated with them. The images were obtained from 8.7 to 18.8 μm with the mid-IR camera CID (Salas et al. 2003) on the 2.1m telescope of the Observatorio Astronomico Nacional at San Pedro Martir (Baja California, Mexico). The images were taken with a scale 0.55″/pix and the mean PSF was 1.5-2.0″(FWHM) close to the diffraction limit. We report as an example in Fig. 1 (left panel) our 18.8μm contours of IRAS 06061+2151 superimposed to the 2MASS Ks image. A young cluster of at least 4 sources has been found centered on the IRAS source (Anandarao et al. 2004). We have found two mid-IR sources coinciding with the source #2 and #4 of Anandarao et al. (2004). The source #4 is at the center of two H2 knots and a high velocity molecular outflow. The mid-IR emission from #2 is extended and coincides with the UCHII and MSX source. The methanol maser is approximately 10″ south of the source #2. The SEDs of both sources are illustrated in Fig. 1 (right panel). The IR spectral indices of source #2 and #4 are α(IR)=1.9 and 2.2 respectively.
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Mescia, L., F. Smektala i F. Prudenzano. "New Trends in Amplifiers and Sources via Chalcogenide Photonic Crystal Fibers". International Journal of Optics 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/575818.

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Rare-earth-doped chalcogenide glass fiber lasers and amplifiers have great applicative potential in many fields since they are key elements in the near and medium-infrared (mid-IR) wavelength range. In this paper, a review, even if not exhaustive, on amplification and lasing obtained by employing rare-earth-doped chalcogenide photonic crystal fibers is reported. Materials, devices, and feasible applications in the mid-IR are briefly mentioned.
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Zorin, Ivan, Jakob Kilgus, Kristina Duswald, Bernhard Lendl, Bettina Heise i Markus Brandstetter. "Sensitivity-Enhanced Fourier Transform Mid-Infrared Spectroscopy Using a Supercontinuum Laser Source". Applied Spectroscopy 74, nr 4 (25.02.2020): 485–93. http://dx.doi.org/10.1177/0003702819893364.

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Fourier transform infrared (FT-IR) spectrometers have been the dominant technology in the field of mid-infrared (mid-IR) spectroscopy for decades. Supercontinuum laser sources operating in the mid-IR spectral region now offer the potential to enrich the field of FT-IR spectroscopy due to their distinctive properties, such as high-brightness, broadband spectral coverage and enhanced stability. In our contribution, we introduce this advanced light source as a replacement for conventional thermal emitters. Furthermore, an approach to efficient coupling of pulsed mid-IR supercontinuum sources to FT-IR spectrometers is proposed and considered in detail. The experimental part is devoted to pulse-to-pulse energy fluctuations of the applied supercontinuum laser, performance of the system, as well as the noise and long-term stability. Comparative measurements performed with a conventional FT-IR instrument equipped with a thermal emitter illustrate that similar noise levels can be achieved with the supercontinuum-based system. The analytical performance of the supercontinuum-based FT-IR spectrometer was tested for a concentration series of aqueous formaldehyde solutions in a liquid flow cell (500 µm path length) and compared with the conventional FT-IR (130 µm path length). The results show a four-times-enhanced detection limit due to the extended path length enabled by the high brightness of the laser. In conclusion, FT-IR spectrometers equipped with novel broadband mid-IR supercontinuum lasers could outperform traditional systems providing superior performance, e.g., interaction path lengths formerly unattainable, while maintaining low noise levels known from highly stable thermal emitters.
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Koptev, Maksim Yu, Alexander E. Zaprialov, Alexey F. Kosolapov, Alexander N. Denisov, Maria S. Muravyeva, Sergey L. Semjonov, Sergey V. Muravyev i Arkady V. Kim. "Visible to Mid-IR Supercontinuum Generation in Cascaded PCF-Germanate Fiber Using Femtosecond Yb-Fiber Pump". Fibers 11, nr 9 (24.08.2023): 72. http://dx.doi.org/10.3390/fib11090072.

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Broadband supercontinuum (SC) fiber sources covering the mid-IR range have many significant applications, largely due to their compactness, reliability, and ease of use. However, most of the existing SC fiber sources cannot boast of either high reliability or a wide bandwidth. Thus, supercontinuum sources based on silica fibers are robust, but are not capable of generating SC in the mid-IR range. Sources based on soft glasses (tellurite, chalcogenide, etc.) generate broadband SC in the mid-IR range but are not used commercially, due to the poor mechanical and chemical characteristics of such fibers. In this work, we propose a new approach consisting of cascade generation of a supercontinuum sequentially in a silica photonic crystal fiber (PCF) and a germanate fiber. Using a standard ytterbium chirped-pulse amplification (CPA) laser system for pumping, we have demonstrated a supercontinuum in the range of 450–2950 nm in PCF and germanate fiber firmly connected by a standard fusion splicing technique. Further optimization of the cascade pump will make it possible to create a compact and reliable all-fiber SC source from the visible to mid-IR range.
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Rozprawy doktorskie na temat "Mid-IR sources"

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Mörz, Florian [Verfasser]. "Ultrafast laser sources : tunable, ultrafast laser sources for near- and mid-IR spectroscopy / Florian Mörz". Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2020. http://d-nb.info/1222515504/34.

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D'AMBROSIO, DAVIDE. "Characterizing a Mid-IR laser source with a molecular beam". Doctoral thesis, Politecnico di Torino, 2019. http://hdl.handle.net/11583/2749554.

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Rame, Jérémy. "Recherche et élaboration de nouveaux matériaux pour les applications laser non-linéaires du moyen infrarouge". Electronic Thesis or Diss., Paris 6, 2014. http://www.theses.fr/2014PA066716.

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Le moyen infrarouge (MIR) présente un fort intérêt technologique du fait de la présence de bandes de transparence de l’atmosphère dans ce domaine. En effet, elles permettent d’envisager de nombreuses applications à longue distance, telles que la détection de gaz ou le brouillage infrarouge de missiles pour la sécurité des aéronefs civils ou militaires. Les sources paramétriques optiques font partie des technologies de choix pour la génération d’impulsions laser dans ce domaine. Elles nécessitent l’emploi de cristaux non-linéaires pour convertir des signaux laser, du proche infrarouge vers le MIR, dont un état de l’art est présenté dans cette étude. AgGaGeS4 est un candidat prometteur pour ces applications. L’élaboration de ce matériau par la technique de synthèse chimique double zone et la cristallogenèse par la technique Bridgman-Stockbarger est ici présentée. Des lingots d’AgGaGeS4 (φ=28 mm et L=70 mm) ont pu être obtenus. Les facteurs clés pour le développement de ces cristaux ont été mis en évidence, en particulier le contrôle de la volatilité du GeS2. Par ailleurs, un dispositif permettant d’améliorer la méthode de synthèse chimique, en mesurant en temps réel les variations de pression au cours du procédé, est proposé. Concernant ZnGeP2, matériau de référence dans ce domaine, des simulations ab initio ont été réalisées pour étudier l’influence de substitutions ioniques sur les propriétés de ce composé. En complément, des monocristaux de ZGP:Sn ont été élaborés et caractérisés. L’ajout d’étain a permis d’améliorer significativement la transmission optique vers 2 μm, longueur d’onde de pompage de ce cristal
Mid-infrared laser sources have attracted a particular attention due to their potential applications in different fields, such as remote chemical sensing or infrared counter-measures for civilian or military aircrafts safety. One way to produce such sources is the down conversion process in optical parametric oscillators using nonlinear crystals. AgGaGeS4 is a promising candidate for these applications. The chemical synthesis and crystal growth steps of this material processing are presented in this study. Ingots with 28 mm diameter and 70 mm length were grown. The key issue of AgGaGeS4 processing is the control of melt decomposition at high temperature due to the high volatility of GeS2. The influence of GeS2 volatility on melt stoichiometry during the AgGaGeS4 processing is outlined, and solutions to improve crystals quality by controlling this volatility are presented. Otherwise, we present the development of a device which aim to improve the chemical synthesis process by controlling the pressure variations during the chemical reaction. Main interests of this device are to study the chemical reaction which occurs during the process and control the pressure variations during the chemical reaction. Furthermore, ab initio calculations were performed in order to study the properties of ZnGeP2 which is a benchmark material for mid-IR laser conversion. The effect of ionic substitution on ZnGeP2 properties was studied. Moreover, ZnGeP2:Sn crystals were elaborated and characterized. It was demonstrated that ionic substitutions with tin allowed significantly improvements on the crystal transmission around the pump wavelength at 2.05 μm
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Van, de walle Aymeric. "Source paramétrique dans l'infrarouge moyen à haute cadence". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLO009/document.

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Ce manuscrit décrit l’étude et la mise en œuvre d’une source laser ultrarapide à taux de répétition élevé dans l’infra-rouge moyen, pour des applications à la physique des champs forts et à la spectroscopie moléculaire multidimensionnelle. Cette source est basée sur le phénomène d’amplification paramétrique optique à dérive de fréquence, qui permet la génération d’impulsions de quelques cycles optiques.Tout d’abord, nous présentons les applications de ces sources, ainsi que leurs paramètres importants, débouchant sur un cahier des charges pour la source à l’étude. Un état de l’art des sources paramétriques présentées dans la littérature scientifique nous permet ensuite d’appréhender la diversité des architectures et des performances atteintes. En particulier, nous soulignons les points cruciaux que sont la nature et les performances du laser de pompe, le mécanisme de génération du signal à amplifier, ainsi que la robustesse de la synchronisation temporelle entre le signal et la pompe.Nous étudions ensuite la possibilité d’émettre un signal autour de la longueur d’onde de 1,55 µm à partir d’impulsions femtoseconde de pompe à 1,03 µm par génération de supercontinuum dans un cristal massif de YAG. Nous menons ainsi une étude détaillée des propriétés de la partie infra-rouge du supercontinuum obtenu, en termes de contenu spectral, cohérence, propriétés statistiques tir à tir et long terme, et propriétés spatiales. Cette étude nous permet de conclure sur la validité de cette approche pour générer le signal à amplifier.Nous arrivons donc à définir une architecture inédite basée sur l’utilisation d’un laser de pompe basé sur un amplificateur à fibre dopée ytterbium de forte énergie délivrant des impulsions de 300 fs 400 µJ à la cadence de 125 kHz. La durée courte rendue possible par le choix de cette technologie de pompe nous permet de bénéficier d’un certain nombre d’avantages importants : la génération efficace de supercontinuum autour de 1,55 µm, ce qui entraine une synchronisation temporelle très robuste entre pompe et signal. D’autre part le couple étireur – compresseur est constitué de simples lames de matériaux massifs, ce qui permet une grande efficacité et une gestion simplifiée de la phase spectrale. Enfin, la courte durée de pompe augmente le seuil de dommage en intensité crête, ce qui permet l’utilisation de cristaux non linéaires courts et augmente la bande spectrale d’amplification. Des expériences supplémentaires sont menées pour étudier les phénomènes limitant la puissance au sein des cristaux de MgO:PPLN. Les étages d’amplification sont tous réalisés en géométrie colinéaire, ce qui permet d’utiliser le signal et l’idler sans introduction de chirp angulaire. Toutes ces caractéristiques permettent la génération de deux faisceaux en sortie portant des impulsions de 50 fs 20 µJ à 1550 nm et 70 fs 10 µJ à 3,1 µm
This thesis describes the design and construction of an ultrafast high repetition rate laser source in the mid-IR, for applications in strong-field physics and multidimensional molecular spectroscopy. This source is based on optical parametric chirped-pulse amplification, allowing the generation of few-cycle pulses.We first present some applications of these lasers, along with important parameters, to define specifications for the considered source. We then briefly outline the state of the art of similar ultrafast sources described in the literature, to highlight the variety of architectures and performances. In particular, several key points are identified, namely the nature and performances of the pump laser source, the method to generate a seeding signal, and the robustness of temporal synchronization between pump and signal pulses.We proceed to study the possibility of emitting a seed signal around 1.55 µm wavelength by supercontinuum generation in a bulk YAG crystal from femtosecond pump pulses at 1.03 µm. A detailed analysis of the properties of the infrared spectral content of the supercontinuum is carried out, focusing on spectral bandwidth, coherence, shot-to-shot and long term stability, and spatial properties. This work allows us to conclude that supercontinuum generation is a valid approach to generate the seed signal.This leads us to define a novel architecture built around an ytterbium-doped fiber femtosecond pump source delivering 300 fs 400 µJ pulses at a repetition rate 125 kHz. The short pump pulse duration compared to bulk Yb:YAG or Nd:YVO4 based systems results in a number of important advantages. First, it allows efficient seeding at 1550 nm using supercontinuum generation directly from the pump pulses in a bulk YAG crystal, resulting in extremely robust passive pump – signal synchronization. The short pump pulse duration also allows the use of millimeter to centimeter lengths of bulk materials to provide stretching and compression for the signal and idler, which minimizes the accumulation of higher-order spectral phase. Finally, the shorter pump pulse duration increases the damage peak intensity, permitting the use of shorter nonlinear crystals to perform the amplification, which increases the spectral bandwidth of the parametric process. Additional experiments are performed to sort out the phenomena that limit power scaling in MgO:PPLN crystals. The OPCPA stages are all operated in collinear geometry, allowing the use of both signal and idler without the introduction of angular chirp on the latter. These points result in the dual generation of 70 fs 23 µJ signal pulses at 1550 nm and 60 fs 10 µJ idler pulses at 3070 nm from a simple setup
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Ayoub, Anas. "Sources laser ultrarapides performantes dans le moyen IR et le Tz". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR044.

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La sonde atomique tomographique est un instrument d’analyse de la matière à trois dimensions avec une résolution atomique. Cet instrument s’appuie sur l’effet de champ électrique généré à l’extrémité d’un échantillon taillé sous la forme d’une aiguille nanométrique pour faire évaporer les atomes de surface qui sont collectés par un détecteur à deux dimensions. La mesure du temps de vol des ions dont l’évaporation est déclenchée par une impulsion électrique ou optique permettent de remonter à la composition chimique en plus de la localisation 3D des atomes. Dans les sondes atomiques actuelles, l’évaporation atomique est déclenchée par un laser ultrarapide émettant dans l’UV. Cependant, l’interaction de la lumière UV avec la matière induit un échauffement thermique qui limite la résolution en masse de l’instrument et empêche son exploitation pour l’analyse de matériaux fragiles comme les composants biocompatibles. Ces travaux de thèse visent à étudier des solutions pour favoriser l’évaporation rapide tout en inhibant les effets thermiques indésirables dans le cadre d’une sonde atomique laser. Notre approche consiste à exploiter des impulsions ultracourtes dans le domaine du moyen infrarouge ou du THz en raison de leur grande énergie pondéromotrice associée à une faible énergie de photon. Ce manuscrit rapporte sur le développementd’un banc de génération et caractérisation d’impulsions THz intenses. Le couplage de ces rayonnements avec une nano-pointe métallique polarisée négativement a permis de caractériser le champ proche induit à la surface de la nano-pointe qui est fortement modifié par l’effet d’antenne de cette dernière. La deuxième partie rapporte sur le développement d’une source laser ultrarapide de haute cadence accordable dans le moyen infrarouge autour de 3 mm en exploitant des fibres en verre fluoré
The atome probe tomography is an instrument for analyzing matter in three dimensions with atomic resolution. This instrument relies on the effect of an electric field generated at the end of a sample cut into the shape of a nanoscale needle to evaporate the surface atoms which are collected by a two-dimensional detector. The measurement of the time of flight of the ions whose evaporation is triggered by an electrical or optical pulse makes it possible to measure the chemical composition in addition to the 3D localization of the atoms. In current atome probes, atomic evaporation is triggered by a high-speed laser emitting in the UV. However, the interaction of UV light with matter induces thermal heating which limits the mass resolution of the instrument and prevents its use for the analysis of fragile materials such as biocompatible components. This thesis work aims to study solutions to promote rapid evaporation while inhibiting unwanted thermal effects of the laser in atome probe. Our approach consists in exploiting ultrashort pulses in the mid-infrared or THz domain due to their high ponderomotive energy associated with low photon energy. This manuscript reports on the development of a bench for the generation and characterization of intense THz pulses. Coupling these radiations with a negatively polarized metallic nanotip has made it possible to characterize the near field induced at the surface of the nanotip, which is strongly modified by the antenna effect. The second part reports on the development of an ultra-fast laser source tunable in the mid-infrared around 3 mm using fluoride glass fibers
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Zhou, Gengji [Verfasser], i Franz X. [Akademischer Betreuer] Kärtner. "Power scaling of ultrafast mid-IR source enabled by high-power fiber laser technology / Gengji Zhou ; Betreuer: Franz Kärtner". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2017. http://d-nb.info/1143868781/34.

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Huijts, Julius. "Broadband Coherent X-ray Diffractive Imaging and Developments towards a High Repetition Rate mid-IR Driven keV High Harmonic Source". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS154/document.

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Des sources des rayons XUV (1-100 nm) sont des outils extraordinaires pour sonder la dynamique à l’échelle nanométrique avec une résolution femto- voire attoseconde. La génération d’harmoniques d’ordre élevé (GH) est une des sources majeures dans ce domaine d’application. La GH est un processus dans lequel une impulsion laser infrarouge femtoseconde est convertie, de manière cohérente, en fréquences élevées dans le domaine EUV par interaction hautement non-linéaire dans un atome, une molécule et plus récemment, dans un cristal. La GH possède une excellente cohérence spatiale qui a permis de réaliser des démonstrations impressionnantes en imagerie sans lentille. Pour accroître le potentiel de ces sources, des défis sont à relever : leur brillance et énergie de photon maximum doivent augmenter et les techniques d’imagerie sans lentille doivent être modifiées pour être compatibles avec l’importante largeur spectrale des impulsions attosecondes émise par ces sources. Cette thèse présente une nouvelle approche dans laquelle des figures de diffraction large bande, i.e. potentiellement attosecondes, sont rendues monochromatiques numériquement. Cette méthode est basée uniquement sur la mesure du spectre de la source et la supposition d’un échantillon spatialement non-dispersif. Cette approche a été validée tout d’abord dans le visible, à partir d’un supercontinuum. L’échantillon binaire est reconstruit par recouvrement de phase pour une largeur spectrale de 11 %, là où les algorithmes usuels divergent. Les simulations numériques montrent aussi que la méthode de monochromatisation peut être appliquée au domaine des rayons X, avec comme exemple un masque semi-conducteur utilisé en de lithographie EUV. Bien que la brillance « cohérente » de la source actuelle (qui progresse) reste insuffisante, une application sur l’inspection de masques sur source Compton est proposée. Dans une extension de ces simulations un masque de lithographie étendu est reconstruit par ptychographie, démontrant la versatilité à d’autres techniques d’imagerie sans lentille. Nous avons également entamé une série d’expérience dans le domaine des X-durs sur source synchrotron. Les figures de diffraction après monochromatisation numérique semblent prometteuses mais l’analyse des données demandent des efforts supplémentaires. Une partie importante de cette thèse est dédiée à l’extension des sources harmoniques à des brillances et énergies de photon plus élevées. Ce travail exploratoire permettrait la réalisation d’une source harmonique compacte pompée par un laser OPCPA dans le moyen infrarouge à très fort taux de répétition. Les longueurs d’onde moyen infrarouge (3.1 μm dans ce travail de thèse) sont favorables à l’extension des énergies des photons au keV et aux impulsions attosecondes. Le but est de pouvoir couvrir les seuils d’absorption X et d’améliorer la résolution spatio-temporelle. Cependant, deux facteurs rendent cette démonstration difficile: le nombre de photons par impulsion de la source OPCPA est très limité et la réponse du dipôle harmonique à grande longueur est extrêmement faible. Pour relever ces défis plusieurs configurations expérimentales sont explorées : génération dans un jet de gaz ; génération dans une cellule de gaz ; compression solitonique et la génération d’harmoniques combinées dans une fibre à cristal photonique ; compression solitonique dans une fibre à cristal photonique et génération d’harmoniques dans une cellule de gaz. Les premiers résultats expérimentaux sur la compression solitonique jusqu’à 26 femtosecondes et des harmoniques basses jusqu’à l’ordre sept sont présentésEn résumé, ces résultats représentent une avancée vers l’imagerie nanométrique attoseconde sans lentille basée sur des algorithmes « large bande » innovants et une extension des capacités de nouvelles sources harmoniques ‘table-top’ au keV pompées par laser OPCPA
Soft X-ray sources based on high harmonic generation are up to now unique tools to probe dynamics in matter on femto- to attosecond timescales. High harmonic generation is a process in which an intense femtosecond laser pulse is frequency upconverted to the UV and soft X-ray region through a highly nonlinear interaction in a gas. Thanks to their excellent spatial coherence, they can be used for lensless imaging, which has already led to impressive results. To use these sources to the fullest of their potential, a number of challenges needs to be met: their brightness and maximum photon energy need to be increased and the lensless imaging techniques need to be modified to cope with the large bandwidth of these sources. For the latter, a novel approach is presented, in which broadband diffraction patterns are rendered monochromatic through a numerical treatment based solely on the spectrum and the assumption of a spatially non-dispersive sample. This approach is validated through a broadband lensless imaging experiment on a supercontinuum source in the visible, in which a binary sample was properly reconstructed through phase retrieval for a source bandwidth of 11 %. Through simulations, the numerical monochromatization method is shown to work for hard X-rays as well, with a simplified semiconductor lithography mask as sample. A potential application of lithography mask inspection on an inverse Compton scattering source is proposed, although the conclusion of the analysis is that the current source lacks brightness for the proposal to be realistic. Simulations with sufficient brightness show that the sample is well reconstructed up to 10 % spectral bandwidth at 8 keV. In an extension of these simulations, an extended lithography mask sample is reconstructed through ptychography, showing that the monochromatization method can be applied in combination with different lensless imaging techniques. Through two synchrotron experiments an experimental validation with hard X-rays was attempted, of which the resulting diffraction patterns after numerical monochromatization look promising. The phase retrieval process and data treatment however require additional efforts.An important part of the thesis is dedicated to the extension of high harmonic sources to higher photon energies and increased brightness. This exploratory work is performed towards the realization of a compact high harmonic source on a high repetition rate mid-IR OPCPA laser system, which sustains higher average power and longer wavelengths compared to ubiquitous Ti:Sapphire laser systems. High repetition rates are desirable for numerous applications involving the study of rare events. The use of mid-IR wavelengths (3.1 μm in this work) promises extension of the generated photon energies to the kilo-electronvolt level, allowing shorter pulses, covering more X-ray absorption edges and improving the attainable spatial resolution for imaging. However, high repetition rates come with low pulse energies, which constrains the generation process. The generation with longer wavelengths is challenging due to the significantly lower dipole response of the gas. To cope with these challenges a number of experimental configurations is explored theoretically and experimentally: free-focusing in a gas-jet; free-focusing in a gas cell; soliton compression and high harmonic generation combined in a photonic crystal fiber; separated soliton compression in a photonic crystal fiber and high harmonic generation in a gas cell. First results on soliton compression down to 26 fs and lower harmonics up to the seventh order are presented.Together, these results represent a step towards ultrafast lensless X-ray imaging on table-top sources and towards an extension of the capabilities of these sources
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Lin, Yan-Rung, i 林雁容. "Tunable Mid-IR Difference Frequency Generation Source and Precise Spectroscopy of Helium Hydride Molecular Ion HeH+". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/68647931165727578440.

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博士
國立清華大學
物理學系
91
In this dissertation, we are interested in molecular ion HeH+. Second only to H2+, the helium hydride HeH+, hydrogen deuterium HD and their isotopes are the simplest heternuclear molecules. They are the good theoretical testing ground and also play important roles in the astrophysics. It is composed of the two most abundant elements in the universe. Hence it has been suggested presenting in the astronomical objects. At present, the accuracy in theoretical and experimental results is about 30 MHz. We have achieved an improved accuracy to a few MHz. A stable and narrow linewidth DFG (Difference Frequency Generation) source in mid-IR was set up with power 1.3~1.5 mW and the accuracy of about 1 MHz. The DFG source was based on a Nd:YAG laser of power 1.2 W at 1064 nm, and a Ti:Sapphire laser with power >1.5 W at 780-870 nm. A multi-channel periodically poled LiNbO3 (PPLN) was used to generate the difference frequency within the tuning range 2.92~4.77 μm. The method which we used to get the frequency of the DFG source was to know the individual frequency of Ti:Sapphire and two YAG lasers, with the aid of hyperfine transitions of iodine molecule. Before measuring the transition frequency of HeH+, we have tested the accuracy of system by measuring the second derivative saturation absorption of methane F2(2), P(7) line of the band at 3.39 μm. It is one of the recommended frequencies. Our measured result was 88376182.694(40) MHz and it is 1.1 MHz larger than the recommended value 88376181.60018(27) MHz. At present, we do not know the origin of the discrepancy. However, we can conclude that the frequency accuracy of our DFG source is ~1MHz. In addition to F2(2) P(7) line of the band, we have also measured the frequencies of E and A2 transitions of the P(7) line . Five spectra, R(0) to R(4), in fundamental band of HeH+ in the electronic ground state were measured by the concentration modulation. The sensitivity in the present experimental setup was about 10^-8 cm-1/Hz^0.5 . Meanwhile, we have also investigated some physical properties of HeH+ in the discharge tube. In the future, we expect to improve the accuracy of the transition frequency of HeH+ to ~1 MHz by observing the saturation spectroscopy with cavity enhancement technique. We plan to remeasure the transition frequencies of other simple molecules such as HD and H3+. Both HD and H3+ play import roles in the quantum mechanics calculation and in the astrophysics.
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Tzu-HanSu i 蘇子涵. "Saturation spectroscopy of CO2 at 4.19 um using a mid-IR hollow fiber and a DFG source". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/34877339619071190472.

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碩士
國立成功大學
光電科學與工程學系
104
In this experiment, we build up a new difference frequency generation laser source with the wavelength tuning range from 3.99 μm to 4.17 μm, and the maximum output power is 3 mW at 4.19 μm. Then, we couple the mid-infrared light into the hollow core fiber to measure the saturated absorption spectroscopy of CO2 R(60) transition. In this thesis, I separate the entire experiment into two parts. The first part is talking about the DFG source, we build up the source with a tunable cw MOPA laser (840-868 nm) and a Nd:YAG laser (1064 nm) with the 10 W fiber amplifier. Two laser beams passing through the Periodically Poled Lithium Niobate (PPLN) crystal generate the DFG source. The second part is the experimental setup of saturated absorption spectroscopy, we couple the mid-infrared light into a hollow core waveguide, 1 m long with the diameter 300 μm, and re-coupled via the concave mirror to serve as the probe beam, and measure the saturated absorption spectroscopy of CO2 R(60) transition on the fundamental band 00^0 1←00^0 0. Simultaneously, analyze the absorption linewidth with Lorentz function, and also record and discuss the beam profiles in this thesis. In the future, we are going to optimal the energy conservation efficiency, change a BaF2 lens with shorter focal length to increase the coupling efficiency, and use lock-in and PID to lock the frequency of MOPA laser on the zero-crossing point of third-derivative saturation dip of CO2 R(60) transition.
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INSERO, GIACOMO. "HIGH PRECISION FREQUENCY MEASUREMENT ON A CO MOLECULAR BEAM USING A 6 UM COHERENT SOURCE REFERENCED TO A FIBER DELIVERED ABSOLUTE STANDARD". Doctoral thesis, 2017. http://hdl.handle.net/2158/1091730.

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The vibrational transition $|v=1, J=1, - angle leftarrow |v=0, J=1, + angle$ in the a$^3Pi_1$ state of CO is measured at the kHz level as 51399115447(3) kHz. The measurement is done on a pulsed, supersonic molecular beam. The achieved relative accuracy is $6cdot 10^{-11}$, more than four orders of magnitude better than previous measurements. The thesis consists of two parts. The first part treats the generation of coherent radiation in the mid-infrared by difference frequency generation of two near-infrared lasers in a custom-made orientation-patterned gallium phosphide (OP-GaP) crystal. This novel nonlinear material is extensively characterized. This crystal is particularly interesting for its wide transparency range, its high nonlinear coefficient, and for the possibility of quasi phase-matching with the widely used 1064-nm lasers. Then, it is explained how the accuracy and the stability of the frequency standard at the national metrological institute (INRIM) is transferred to the 6-micron radiation using a 642-km long fiber link and an optical frequency comb. The mid-IR source is characterized in terms of phase noise power spectral density. The second part of the thesis deals with the experimental setup and the spectroscopic measurement. After a brief discussion of the carbon monoxide energy levels and experimental apparatus, the high precision measurements are presented. The effects of stray fields, mainly magnetic, and of the Doppler shift are extensively discussed.
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Książki na temat "Mid-IR sources"

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Martin, Francis L., i Hubert M. Pollock. Microspectroscopy as a tool to discriminate nanomolecular cellular alterations in biomedical research. Redaktorzy A. V. Narlikar i Y. Y. Fu. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199533053.013.8.

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This article considers the use of microspectroscopy for discriminating nanomolecular cellular alterations in biomedical research. It begins with an overview of some existing mid-infrared microspectroscopy techniques, including FTIR microspectroscopy and Raman microspectroscopy. It then discusses near-field techniques such as scanning near-field optical microscopy, near-field Raman microscopy, and photothermal microspectroscopy (PTMS). It also examines promising alternative sources of IR light, possible advantages of using normal atomic force microscopy probes, experimental procedures for PTMS, and prospects for high spatial resolution in near-field FTIR spectroscopy. Finally, it describes the spectroscopic detection of small particles, along with the use of the analysis paradigm to discriminate nanomolecular cellular alterations in biomedical research.
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Części książek na temat "Mid-IR sources"

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Meyer, J. R., I. Vurgaftman, L. J. Olafsen, E. H. Aifer, W. W. Bewley, C. L. Felix, C. H. Lin i in. "Phase-Matched Second-Harmonic and Cascade Laser Mid-IR Sources". W Intersubband Transitions in Quantum Wells: Physics and Devices, 22–29. Boston, MA: Springer US, 1998. http://dx.doi.org/10.1007/978-1-4615-5759-3_4.

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Ivanov, Misha, Vlad Yakovlev i Ferenc Krausz. "Opportunities for Mid-IR Sources in Intense-Field and Attosecond Physics". W NATO Science for Peace and Security Series B: Physics and Biophysics, 589–98. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6463-0_21.

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Hu, Jonathan, i Curtis R. Menyuk. "Chalcogenide Glass Fibers for Mid-IR Supercontinuum Generation". W The Supercontinuum Laser Source, 479–511. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-06197-4_13.

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Pertot, Yoann, Nicolas Thiré, Raman Maksimenka, Olivier Albert i Nicolas Forget. "100 kHz tunable mid-IR ultrafast sources for high intensity applications". W Emerging Laser Technologies for High-Power and Ultrafast Science. IOP Publishing, 2021. http://dx.doi.org/10.1088/978-0-7503-2536-3ch4.

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MANDAL, KRISHNA C., SUNG H. KANG, MICHAEL CHOI i R. DAVID RAUH. "RARE-EARTH DOPED POTASSIUM LEAD BROMIDE MID-IR LASER SOURCES FOR STANDOFF DETECTION". W Selected Topics in Electronics and Systems, 509–19. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789812835925_0040.

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Ortiga, Souria. "Clear and Private Ad Hoc Retrieval Models on Web Data". W Advances in Computational Intelligence and Robotics, 194–211. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7338-8.ch009.

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During the 1980s, and despite its maturity, the search information (RI) was only intended for librarians and experts in the field of information. Such tendentious vision prevailed for many years. Since the mid-90s, the web has become an increasingly crucial source of information , which has a renewed interest in IR. In the last decade, the popularization of computers, the terrible explosion in the amount of unstructured data, internal documents, and corporate collections, and the huge and growing number of internet document sources have deeply shaken the relationship between man and information. Today, a great change has taken place, and the RI is often used by billions of people around the world. Simply, the need for automated methods for efficient access to this huge amount of digital information has become more important, and appears as a necessity.
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Igor, Vurgaftman. "Quantum Cascade Lasers". W Bands and Photons in III-V Semiconductor Quantum Structures, 491–526. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198767275.003.0013.

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This chapter describes the most commonly used approaches for computing the band structure of active materials with intersubband optical transitions. The physics of quantum cascade lasers (QCLs) is discussed in detail, including the mechanisms that limit the threshold current density, threshold voltage, wall-plug efficiency, and temperature sensitivity of state-of-the-art devices. The important roles of phonon and interface roughness scattering in determining threshold are emphasized. The chapter also compares the performance of QCLs to other mid-IR lasers in considerable detail and makes some conclusions as to which sources are preferred depending on the emission wavelength and application. Finally, the physical principles of laser-based frequency combs, including self-starting frequency-modulated QCL combs, are discussed.
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Streszczenia konferencji na temat "Mid-IR sources"

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Shaw, L. Brandon, Rafael R. Gattass, Jesse Frantz, Vinh Q. Nguyen, Ishwar D. Aggarwal i Jasbinder S. Sanghera. "IR Fiber Mid-IR Raman Amplifier". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/mics.2013.mth1c.6.

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Savchenkov, Anatoliy A., Vladimir S. Ilchenko, Andrey B. Matsko i Lute Maleki. "Integrated Mid-IR Frequency Combs". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/mics.2016.mm1c.3.

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Shaw, Brandon, Rafael R. Gattass, Jas Sanghera i Ishwar Aggarwal. "Mid-IR Fiber Sources". W Advances in Optical Materials. Washington, D.C.: OSA, 2012. http://dx.doi.org/10.1364/aiom.2012.ith3b.1.

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Baudisch, Matthias, Alexandre Thai, Michaël Hemmer i Jens Biegert. "3.3-Octave, Few-Cycle, Mid-IR Source with CEP Stability–Mid-IR Filamentation in Dielectrics". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/mics.2013.mw1c.8.

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Schellhorn, Martin, Georg Stoeppler, Stefano Bigotta, Anne Hildenbrand, Christelle Kieleck i Marc Eichhorn. "High-pulse energy mid-IR ZGP OPO". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/mics.2013.mw3b.1.

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Sanghera, Jas S., Brandon Shaw i Ishwar Aggarwal. "Mid-IR Sources for Sensors". W Optical Sensors. Washington, D.C.: OSA, 2010. http://dx.doi.org/10.1364/sensors.2010.swc1.

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Baltuska, Andrius, Skirmantas Alisauskas, Giedrius Andriukaitis, Fan Guangyu, Tadas Balciunas i Audrius Pugzlys. "Few-Cycle Multi-Millijoule Mid-IR Parametric Amplifiers". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/mics.2013.mw2c.1.

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Zorin, Ivan, Paul Gattinger i Markus Brandstetter. "Advanced spectroscopic instruments based on high-brightness mid-infrared lasers". W Mid-Infrared Coherent Sources. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/mics.2024.mth3c.6.

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In the past decade, mid-infrared lasers emerged as cost-effective alternatives for routine infrared spectroscopy, notable for their brightness and coherence. We review advancements in IR spectroscopy techniques tailored for mid-IR supercontinuum sources.
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Wysocki, Gerard. "Mid-IR Molecular Dispersion Spectroscopy with Quantum Cascade Lasers". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/mics.2013.mth3c.1.

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Gaeta, A. L., i Y. Okawachi. "Silicon-Based Parametric Frequency Combs for the Mid-IR". W Mid-Infrared Coherent Sources. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/mics.2016.mm8c.3.

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Raporty organizacyjne na temat "Mid-IR sources"

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Lam, Yee-Loy. Speckle Free, Low Coherency, High Brightness, and High Pulse Speed Infrared Collimated Light Sources for Mid-IR Target Designator and Hyperspectral Imaging. Fort Belvoir, VA: Defense Technical Information Center, październik 2007. http://dx.doi.org/10.21236/ada482581.

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