Готові списки джерел за темами / Heterodyne effect

Добірка наукової літератури з теми "Heterodyne effect"

Автор: Grafiati
Опубліковано: 8 червня 2024

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  1. Статті в журналах
  2. Дисертації
  3. Частини книг
  4. Тези доповідей конференцій
  5. Звіти організацій

Статті в журналах з теми "Heterodyne effect":

1

Tan, Zhenkun, Jiao Wang, Yingxiu Kong, Sichen Lei, and Pengfei Wu. "An Effective Method for Enhancing Heterodyne Efficiency by Comparing the Effect of Degree of Polarization on an Uplink Path and a Downlink Path." Photonics 9, no. 11 (October 25, 2022): 798. http://dx.doi.org/10.3390/photonics9110798.

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By analyzing the effect of the degree of polarization (DoP) of the partially coherent Gaussian Schell-model (GSM) beam on a heterodyne system of an uplink path and a downlink path, we developed an innovative and noteworthy theory according to which σsy (signal beam waist radius in the y direction component) and δSyy (coherence length of the signal beam in the yy direction component) had a more significant impact on heterodyne efficiency and DoP than the turbulence term on uplink and downlink paths. Namely, the DoP and heterodyne efficiency of an uplink path are higher than that of a downlink path when σsy > 0.02 m or δSyy ≥ 0.03 m. This innovative rule provides an efficient way for increasing the heterodyne efficiency of a signal beam propagating along an uplink or a downlink path channel in satellite-ground communication links in free-space optical heterodyne detection communication.
2

Cuberes, M. Teresa. "Intermittent-Contact Heterodyne Force Microscopy." Journal of Nanomaterials 2009 (2009): 1–5. http://dx.doi.org/10.1155/2009/762016.

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Heterodyne Force Microscopy opens up a way to monitor nanoscale events with high temporal sensitivity from the quasistatic cantilever mechanical-diode response taking advantage of the beat effect. Here, a novel heterodyne ultrasonic force method is proposed, in which the cantilever is driven in amplitude-modulation mode, at its fundamental flexural eigenmode. Ultrasonic vibration in the megahertz range is additionally input at the tip-sample contact from the cantilever base and from the back of the sample. The ultrasonic frequencies are chosen in such a way that their difference is coincident with the second cantilever eigenmode. In the presence of ultrasound, cantilever vibration at the difference frequency is detected. Similarly as in heterodyne force microscopy, it is expected that the phase response yields information with increased sensitivity due to the beat effect.
3

Yamamoto, Naoko, Yuya Shinohara, Hiroyuki Kishimoto, Norihiro Matsumoto, and Yoshiyuki Amemiya. "Dynamics of nanoparticles in elongated rubber investigated with heterodyne XPCS." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1331. http://dx.doi.org/10.1107/s2053273314086689.

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Addition of nanoparticles into rubber is indispensable process for production of rubbery materials, as it improves the viscoelastic and mechanical properties of rubber (reinforcement effect). However, the understanding of reinforcement effect is far from satisfactory in spite of many studies. Further microscopic-scale investigation is required for controlling and improving the properties of rubbery materials. Aiming to construct a microscopic model of filled rubber under elongation, we have investigated nanoparticle dynamics in uniaxially stretched rubber using heterodyne X-ray photon correlation spectroscopy (heterodyne XPCS)[1] at BL03XU, SPring-8, Japan. In heterodyne XPCS, information on the fluctuating and dissipative dynamics of nanoparticles and that on their advective motion are separately extracted from the time correlation of X-ray scattering intensity. The results of heterodyne XPCS experiments showed that the direction of nanoparticles' advective motion corresponds to the macroscopic deformation of the sample in stress relaxation process. Furthermore, we found that chemical bond between nanoparticle and rubber polymer influences the dynamics of nanoparticles. In this presentation, we will show detailed analysis of the heterodyne XPCS results and discuss a microscopic description of filled rubber under elongation. This study was conducted under the approval of the SPring-8 Proposal Advisory Committee (2013A7210, 2013B7259).
4

Reno, Jessica, Bhanu Korremula, and Dominick J. Casadonte. "Heterodyne I: Enhancing sonochemical efficiency through application of the heterodyne effect: An initial study." Ultrasonics Sonochemistry 56 (September 2019): 143–49. http://dx.doi.org/10.1016/j.ultsonch.2019.04.014.

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5

Gershgorin, B., V. Yu Kachorovskii, Y. V. Lvov, and M. S. Shur. "Field effect transistor as heterodyne terahertz detector." Electronics Letters 44, no. 17 (2008): 1036. http://dx.doi.org/10.1049/el:20080737.

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6

Song, Xue, Guofeng Shen, and Dmitry Grishenkov. "A comparative study on detection of polymer-shelled microbubbles by different excitation pulses." Journal of the Acoustical Society of America 154, no. 1 (July 1, 2023): 482–93. http://dx.doi.org/10.1121/10.0020293.

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Contrast agents are widely used in ultrasound imaging. Many imaging techniques have been developed to improve the contrast between tissue and the agents, based on the nonlinear response of microbubbles. In this study, heterodyne excitation was introduced and was compared with traditional sinusoidal signal and chirp excitation for visualizing polymer-shelled microbubbles and degassed water in a tissue-mimicking phantom. Pulse inversion technique was implemented under plane wave (PW) and focused imaging mode. Image enhancement was evaluated by contrast-to-tissue ratio (CTR) at different transmitting peak negative pressures (PNPs). Experimental results showed that heterodyne excitation had a better suppression effect on tissue signals in PW imaging. The CTR reached an approximation of 17 dB at a low peak negative pressure, which was much higher compared to other excitations. In focused wave imaging, a saturation threshold of CTR was observed for the sinusoidal wave burst and chirp excitation at high PNPs. Heterodyne excitation showed considerable contrast-to-noise ratio under both imaging modes. The response of a polymer-shelled microbubble under heterodyne excitation was simulated. Simulations suggest that in future work, specific filters are required to extract the nonlinear components, such as at the two-peak frequencies around fundamental frequency, to achieve a better image enhancement effect.
7

Xiong, Si Ya Dong, Yi Yang, Chao Peng, Zhen Rong Zhang, and Zheng Bin Li. "The Effect of Polarization Control in Loss-Compensated Recirculating Delayed Self-Heterodyne Interferometry Measurement of Laser Linewidth." Applied Mechanics and Materials 303-306 (February 2013): 859–62. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.859.

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In the implementation of the loss-compensated recirculating delayed self-heterodyne interferometry (LC-RDSHI) measurement of laser linewidth, we observe the fluctuations among the different orders of beat spectra, which are not expected according to theoretical analysis and may lead to the distortion of lineshape and inaccurate estimation of the laser linewidth. To explain the observation, we in this paper simplify the polarization model in the recirculating heterodyne ring interferometer containing a polarization controller (PC) and point out the effect of the polarization control in the LC-RDSHI measurement. The simulation result of our model explains well the observed fluctuations.
8

Izumi, Ryo, Yan Jun Li, Yoshitaka Naitoh, and Yasuhiro Sugawara. "Study of high–low KPFM on a pn-patterned Si surface." Microscopy 71, no. 2 (January 11, 2022): 98–103. http://dx.doi.org/10.1093/jmicro/dfab055.

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Abstract Comparative measurements between frequency modulation Kelvin probe force microscopy (FM-KPFM) using low frequency bias voltage and heterodyne FM-KPFM using high frequency bias voltage were performed on the surface potential measurement. A silicon substrate patterned with p- and n-type impurities was used as a quantitative sample. The multi-pass scanning method in the measurements of FM-KPFM and heterodyne FM-KPFM was used to eliminate the effect of the tip–sample distance dependence. The measured surface potentials become lower in the order of the p-type region, n-type region and n+-type region by both FM-KPFM and heterodyne FM-KPFM, which are in good agreement with the order of the work functions of the pn-patterned Si sample. We observed the difference in the surface potentials due to the surface band bending measured by FM-KPFM and heterodyne FM-KPFM. The difference is due to the fact that the charge transfer between the surface and bulk levels may or may not respond to AC bias voltage.
9

Belen’kii, Mikhail S. "Effect of atmospheric turbulence on heterodyne lidar performance." Applied Optics 32, no. 27 (September 20, 1993): 5368. http://dx.doi.org/10.1364/ao.32.005368.

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10

Lin, Yao, John Schill, and Run-Wen Wang. "Instrumental noise effect in an optical heterodyne profiler." Applied Optics 33, no. 22 (August 1, 1994): 5005. http://dx.doi.org/10.1364/ao.33.005005.

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Статті в журналах Дисертації

Дисертації з теми "Heterodyne effect":

1

Moussa, Ildoko. "Etude d'un système de multiplexage fréquentiel d'un faisceau lumineux par modulation acousto-optique." Valenciennes, 1985. http://www.theses.fr/1985VALE0006.

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Le principe consiste à moduler, non pas la source lumineuse, mais le faisceau lui-même. On réalise ensuite un hétérodynage optique entre le faisceau module et une partie non modulée de ce faisceau, prise comme référence. Transmission des deux faisceaux par fibre optique à une photodiode connectée directement à l'entrée d'un récepteur de télévision. Réalisation d'une transmission de trois canaux de télévision par une fibre optique
2

Kamar, Nihad. "Maîtrise de l'entartrage dans des échangeurs de chaleur via l'utilisation de traitements physiques." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0209.

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L'objectif de ce travail est d'étudier l'impact d'un traitement « physique » sur la formation d'un dépôt minéral dans un échangeur de chaleur. Plus particulièrement, on s'intéressera à l'effet des ondes ultrasoniques, ainsi qu'à l'effet d'un traitement électromagnétique. Pour mener à bien cette étude, un pilote expérimental a été mis en place afin de tester ces traitements sur deux types d'échangeur de chaleur, un échangeur à plaques et joints et un échangeur platulaire. Plusieurs paramètres de fonctionnement tels que le débit, la durée et la température ont été testés expérimentalement, afin d'identifier leur influence sur la précipitation du carbonate de calcium et la formation de tartre dans l'échangeur. Pour mettre en évidence l'efficacité des traitements cités, une comparaison a ensuite été réalisée entre des expériences sans aucun traitement et des expériences avec un traitement physique, en utilisant une eau de réseau avec un léger pouvoir entartrant. La solubilité inverse du carbonate de calcium et le chauffage de l'eau dans l'échangeur initient la précipitation du carbonate de calcium dans l'eau ainsi que sur les parois de l'échangeur en contact avec cette eau. Les traitements physiques testés sont le traitement ultrasonique à deux fréquences différentes, le traitement électromagnétique de basse fréquence et de faible intensité, et le couplage traitements ultrasonique et électromagnétique. La première partie de ces travaux s'est portée sur une modélisation numérique, l'une avec Phreeqc interactive pour identifier les phases cristallisées et l'autre avec Comsol Multiphysique 6.0 pour identifier les zones de l'échangeur les plus sensibles à la formation du dépôt. Cela permettra notamment de positionner de façon optimale le dispositif ultrasonique, et de modéliser la dispersion des ondes ultrasoniques dans l'échangeur. Les résultats de l'analyse numérique obtenue par ces modèles ont ensuite été comparés aux mesures expérimentales. Les expériences réalisées permettent de quantifier le dépôt dans l'échangeur (via la dissolution de celui-ci dans une solution d'acide nitrique et le dosage du calcium à l'ICP), ou de qualifier ce dépôt (via un démontage de l'échangeur et des observations du dépôt au microscope). Les résultats obtenus montrent que le traitement ultrasonique permet de réduire d'environ 65% le dépôt, tandis que l'efficacité du champ électromagnétique est de l'ordre de 75%. Le couplage des deux traitements n'est pas bénéfique. A l'heure actuelle, tous les traitements physiques testés permettent une réduction de la quantité de tartre déposé, mais n'empêchent pas la formation du dépôt. Ces traitements n'affectent pas le polymorphisme du carbonate de calcium : dans tous les cas, le dépôt analysé est de la calcite. D'un point de vue industriel, ces traitements permettront de maintenir plus longtemps un bon transfert thermique et de réduire la fréquence de maintenance des échangeurs
In order to study the impact of the heterodyne effect on the formation of mineral deposits from domestic water networks in a heat exchanger, an experimental pilot was set up to test this technology on two types of heat exchangers, plate and joint exchanger and platelet exchanger. Several operating parameters such as flow rate, time, and temperature were experimentally tested in order to identify their influence on calcium carbonate precipitation and scale formation in the exchanger. In order to approve the efficiency of the heterodyne effect, a comparison was made with other physical treatments that were tested on the same pilot, namely: ultrasonic treatment at two different frequencies, low frequency, and low-intensity electromagnetic treatment, and the ultrasonic-electromagnetic coupling. The first part of this work focused on numerical modeling, two software were used, Phreeqc interactive and COMSOL Multiphysics 6.0. On the one hand identify the nature of crystallized polymorphism, whether at the pilot-scale or at the industrial scale. And on the other hand to identify the sensitive areas for the formation of the deposit in order to know the location of the ultrasonic system, and to model the dispersion of the ultrasonic waves at different frequencies and power, either in the water or in the metallic surfaces of the exchanger. The results of the numerical analysis obtained by these models were then compared to the experimental measurements.A series of laboratory-scale experiments, with or without the physical treatment, is performed on an exchanger that has been insulated from the outside with an insulating cover and equipped with thermocouples in order to evaluate the impact of the physical treatment tested on the heat transfer. 100 Liters of water with a scaling capacity (30°F) was heated to 50°C within the exchanger for 72 hours in a closed circuit. Due to the high content of dissolved calcium carbonate and the decrease of its solubility when the temperature increases, a precipitate of calcium carbonate forms inside the heat exchanger, but also in the water, as well as on the walls of the exchanger. At the end of each experiment, the deposit is dissolved in 5% (vol.) nitric acid and analyzed by ICP-AES spectroscopy to perform a complete material balance and determine the amount of scale precipitated on the exchanger plates. A dismantling of the exchanger was carried out in each type of test in order to analyze the distribution of the deposit in the whole of the plates by 3D digital microscopy and confocal microscopy, to analyze the precipitated polymorphism by RAMAN spectroscopy and scanning electron microscopy, and the size distribution of the precipitated particles by laser granulometry. The results obtained show that the heterodyne-guided waves allow reducing 65,46% of the deposit. On the other hand, the treatment that allows better reduction is the electromagnetic treatment with a percentage of reduction of 76,83%, without changing the nature of polymorphism. At present, all the physical treatments tested allow a reduction in the amount deposited, but do not prevent the total formation of the deposit. These methods aim to minimize the occurrence of fouling. They are preventive rather than corrective methods
3

Malnou, Maxime. "High-Tc Josephson mixers for Terahertz detection." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066260/document.

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Cette thèse porte sur la fabrication et la caractérisation d'un mélangeur hétérodyne, à partir d'YBa2Cu3O7, un matériau supraconducteur à haute température critique. Nous avons évalué son potentiel pour la détection d'ondes térahertz. La physique complexe des jonctions irradiées a été correctement décrite en modifiant légèrement les équations quasi-classiques d'Usadel, originellement développées pour les supraconducteurs inhomogènes à basse température critique. Les mesures de transport électronique ont montré que nos dispositifs respectent le modèle de la jonction résistivement shuntée. Nous avons expliqué leur fonctionnement à haute fréquence au moyen du modèle à trois ports, et démontré la détection d'ondes jusqu'à 400 GHz. Nous avons identifié l'efficacité de conversion du mélange hétérodyne comme le produit de trois termes : deux rendent compte des adaptations d'impédances en entrée et sortie du mélangeur, le troisième caractérise la conversion à basse fréquence des signaux térahertz. La puissance de l'oscillateur local nécessaire, l'étendue dynamique du mélangeur ainsi que son efficacité de conversion ont été mesurées, s'accordant bien avec les simulations numériques. Le recours à un réseau de jonctions Josephson synchronisées est incontournable pour parvenir à créer un oscillateur local puissant et spectralement fin à partir de l'oscillation propre des jonctions. Nous avons identifié le verrouillage par une boucle externe comme l'unique mécanisme efficace de synchronisation et simulé son effet. Enfin nous avons mesuré la première signature d'une synchronisation dans un réseau à deux dimensions de jonctions irradiées
In this thesis, we used a high-Tc superconducting material, YBa2Cu3O7, to make a heterodyne mixer. We aimed at evaluating its ability for terahertz detection. We also worked towards the fabrication of an on-chip local oscillator, designed with an array of Josephson junctions. The originality of this study stems from a unique way of engineering Josephson junctions, based on ion irradiation. We described the complex physics of ion irradiated Josephson junctions through a modified version of quasi-classical Usadel equations, which have originally been derived for non-homogenous low-Tc superconductivity. The d-c electronic transport measurements showed that our irradiated Josephson junctions are well described by the resistively shunted junction model. Furthermore, we explained the high-frequency mixing operations with the three-port model, and proved the heterodyne detection of signals up to 400 GHz. We identified the heterodyne conversion efficiency as a product of three terms: two depending on impedance mismatches and the third one characterizing the intrinsic down-conversion ability of the Josephson junction. The dynamic range of the mixer, its conversion efficiency and its dependence on local oscillator power were measured and found to be in agreement with simulations. An array of synchronized junctions is necessary to create a powerful and spectrally pure local oscillator from Josephson oscillations. We identified the external locking as the only efficient mechanism to synchronize YBa2Cu3O7 irradiated junctions, showing its effect in simulated systems. We also reported a first evidence of synchronization in a two dimensional array of irradiated Josephson junctions
4

Dremetsika, Evdokia. "Nonlinear optics in graphene: Detailed characterization for application in photonic circuits." Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/264211.

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In the quest for ultrathin materials compatible with CMOS technology for all-optical signal processing applications in integrated photonics, graphene appears to be a promising candidate, with broadband1 optical properties and a high and broadband optical nonlinearity. However, researchers do not agree on the value of its nonlinear refractive index, and commonly used characterization methods do not provide a clear picture of the optical nonlinearity, in terms of its tensor nature or relaxation time. In the first part of this thesis, apart from the previously used Z-scan method, we have also used the ultrafast Optical Kerr Effect method coupled to Optical Heterodyne Detection (OHD-OKE) for the characterization of the third order optical nonlinearity of monolayer CVD graphene at telecom wavelengths. This method allows to separately measure the real and the imaginary part of the third-order nonlinearity, as well as their dynamics. With respect to the Z-scan method, OHD-OKE presents the major advantage of being robust against inhomogeneities of the sample. As such, we have demonstrated that graphene has a negative nonlinear refractive index, contrary to previously reported results. In addition, we have studied the real and imaginary part of graphene’s nonlinearity, when electrostatic gating is applied to change the chemical potential of graphene. Furthermore, we have proposed an enhanced version of the OHD-OKE method, together with the appropriate theoretical framework, in order to extract the tensor elements of the nonlinearity including the out-of-plane tensor elements. In particular, we have measured separately the time response of the two main tensor elements of the nonlinear susceptibility and we have experimentally verified that the out-of-plane tensor components are negligible. In the second part of this thesis, we have investigated, from an experimental point of view, the use of the nonlinear optical response of graphene for all-optical switching applications in integrated photonics. Namely, we have designed simple silicon nitride waveguide structures that constitute basic building blocks of switching devices, which were then fabricated and covered by graphene patches. Finally, we have experimentally tested the graphene-covered structures at low and high power levels and discussed the results.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished
5

Crotty, Maureen. "Signal to Noise Ratio Effects on Aperture Synthesis for Digital Holographic Ladar." University of Dayton / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1355245759.

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6

Wang, Junyang. "Dicke narrowing and speed-dependent effects in dispersion signals : Influence on assessment of concentration and spectral parameters by noise-immune cavity-enhanced optical heterodyne molecular spectrometry." Doctoral thesis, Umeå universitet, Institutionen för fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-70235.

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Laser spectroscopic techniques have, during the last decades, demonstrated an extraordinary capability for sensitive detection of molecular constituents in gas phase. Since spectra from such techniques constitute unique and characteristic signatures for each type of species, these techniques enable investigations of molecular structures as well as detection of the presence of species in a gas mixture. They are therefore used for a variety of application, from fundamental studies to the assessment of gas concentrations. In fact, quantitative assessments of gas concentrations by laser-based techniques are constantly gaining in popularity, primarily due to properties such as high sensitivity and selectivity and an ability to perform non-invasive measurement. Moreover, investigations of isolated molecular transitions under different conditions provide excellent means to obtain a comprehensive understanding of spectral broadening mechanisms, which is of importance for, for example, environmental sciences and remote sensing applications. In fundamental studies, spectroscopic parameters are often retrieved from fits of a model function of the technique used, which in turn is based upon a suitable lineshape function. In order to obtain parameter values with highest possible accuracy, it is of importance to use the lineshape model that most correctly can predict the measured spectra. Even though the Voigt function is the most commonly used lineshape model when both Doppler and collision broadenings are present, it is not always suitable when spectroscopic parameters are to be assessed with high precision. This thesis represents a thorough investigation of Dicke narrowing and speed-dependent effects, which are phenomena that are not accounted for by the conventional Voigt profile. For the first time, it is demonstrated that both these effects take place not only in absorption but also in the dispersion mode of detection. Their dispersion lineshape functions are first theoretically presumed and explicitly given before they are validated experimentally by the noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS). By using the models developed, it is also shown that although the two modes of detection, absorption and dispersion, both can provide good quality of fits, they do not always provide identical spectroscopic parameters. A detailed analysis under which conditions they do so, and subsequent recommendations of their use, are presented. It also describes the instrumental implementation of a distributed-feed-back (DFB) laser-based NICE-OHMS instrumentation, which constitutes an important step towards the further development of this technique. Due to the wide tunability of the DFB laser, the setup is capable of extending the working range of NICE-OHMS into the collision broadening region, which, in turn, allows for precise spectroscopic studies. The use of a fiber-coupled DFB laser also provides a compact NICE-OHMS system. The minimum detectable on-resonance absorption was assessed to 2× 10-10 cm-1 for a 70 s integration time.
7

Vadalà, Giovanni. "Disorder, propagation and non-linear effects in photonic crystal waveguides." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3422364.

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The present work would like contribute to the research in this area, by offering some results on the optical properties, disorder and non-linear effects on wave propagation in semiconductor-based two-dimensional photonic crystal waveguides. The aim is to lead the reader from the basic concepts of photonic crystals (Chapter 1), up to the properties of a 2D photonic crystal (Chapter 2) and the defect line induced waveguide in a 2D photonic crystal (Chapter 3). The propagation properties, the unusual dispersion relation, and the particular regime, known as Slow Light regime, will be analyzed depthly. Particular attention is devoted to model the extrinsic disorder induced by the fabrication process and its impact on the propagation properties of the waveguide (Chapter 4). In the last two chapters, the focus will be on two techniques to characterize photonic crystal waveguides. The first tool is the Time-Wavelength Reflectance Map (Chapter 5), developed with Thales Research and Technology, Paris, France, that permits to evaluate the propagation properties of the waveguide as function of the wavelength showing us a deep physical insight for understanding the role of disorder induced scattering and how it is connected to dispersion. In Chapter 6, a laboratory setup will be presented, based on the Heterodyne Pump-Probe technique, used in a set of experiments at DTU Fotonik, with the main objective to investigate on the Slow Light regime.
Questo lavoro di tesi presenta alcuni nuovi risultati sulle proprietà ottiche e sugli effetti del disordine sulla propagazione in guide d'onda a cristallo fotonico bidimensionale. Lo studio parte dai concetti di base dei cristalli fotonici (Cap. 1), quali la loro struttura a bande, fondamentali per comprendere appieno le proprietà dei cristalli fotonici bidimensionali (Cap. 2). Nel Cap. 3 sono approfondite le proprietà di propagazione della luce nelle guide d'onda realizzate in cristalli bidimensionali, in particolare la loro tipica relazione di dispersione e il regime di propagazione noto come regime di Luce Lenta (Slow Light regime). Nello stesso capitolo, si introduce, inoltre, un modello teorico per il Four-Wave Mixing, fenomeno non lineare solo recentemente osservato in questo tipo di guide. Il Cap. 4 introduce brevemente i processi di fabbricazione per questi dispositivi; vengono quindi discussi i punti critici di tali processi, modellizzati come disordine estrinseco, e l'impatto che questi hanno sulle proprietà di propagazione della guida. Gli ultimi due capitoli sono relativi alla parte sperimentale di questo lavoro. Sono state infatti studiate due tecniche per la caratterizzazione delle guide d'onda a cristallo fotonico. La prima è la mappa di riflettanza tempo-lunghezza d'onda (Cap. 5), sviluppato presso Thales Research and Technology (Paris, France), che permette di valutare le proprietà di propagazione della guida in funzione della lunghezza d'onda e l'impatto della dispersione indotta dal disordine estrinseco della guida. La seconda è la tecnica Heterodyne Pump-Probe, utilizzato presso il Dipartimento DTU Fotonik, Copenhagen, in una serie di esperimenti atti a indagare il regime di luce lenta e i ritardi ottenibili in tale regime.
8

Robson, Laura E. "The Spatial Ecology of Eastern Hognose Snakes (Heterodon platirhinos): Habitat Selection, Home Range Size, and the Effect of Roads on Movement Patterns." Thesis, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20452.

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Habitat loss is the greatest contributor to the decline of species globally and thus understanding habitat use and the consequences fragmentation has on biodiversity is a fundamental step towards management and recovery. I conducted a radio-telemetry study to examine the spatial ecology and the effects of roads on Eastern Hognose Snakes (Heterodon platirhinos), a species at risk, in the Long Point Region of Ontario, Canada. I tested habitat selection at multiple spatial scales and I found that within the home range, snakes avoided agricultural land and selected open sand barrens, particularly for nesting. At the local scale, snakes avoided mature overstory trees and used younger patches of forest. Used locations had more woody debris, logs and low-vegetative coverage than locations selected at random. Eastern Hognose Snakes also showed avoidance of paved road crossings in their seasonal movements, but readily crossed unpaved roads. Management efforts for this species at risk should be placed on the conservation of sand barrens and on the construction of road underpasses to prevent genetic isolation of populations.
9

Feautrier, Philippe. "Jonctions SIS en Nb/Al2O3/Nb pour des récepteurs en radioastronomie millimétrique et submillimétrique." Phd thesis, Grenoble 1, 1992. http://tel.archives-ouvertes.fr/tel-00725267.

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Pour préparer les futures missions sur satellites en radioastronomie, le CNES est responsable d'un projet de ballon stratosphérique appelé PRONAOS-SMH pour lequel notre laboratoire doit construire le récepteur à 380 GHz. Ce projet est décrit dans l'introduction. Dans le premier chapitre, j'expose les bases de la supraconductivité, de l'effet Josephson et du fonctionnement du mélangeur SIS. Le chapitre II développe la technologie utilisée pour la fabrication des jonctions SIS: les principes de l'évaporation, de la pulvérisation, de la gravure et de la photolithographie y sont expliqués. Le troisième chapitre est plus particulièrement consacré à la description et à l'optimisation du procédé de fabrication des jonctions en Nb/AI-A1Ox/Nb. Des jonctions fiables de petite dimension (1 micron carré) et de forte densité de courant sont obtenues. Les études nécessaires pour parvenir à ce résultat sont détaillées. L'intégration de ces jonctions dans des récepteurs millimétriques et submillimétriques est décrite dans le chapitre IV. Les premiers résultats obtenus dans le récepteur à 380 GHz sont prometteurs : une température de bruit de 310 K DSB pour le récepteur dans son ensemble a été mesurée à 374 GHz.
10

Schoelkopf, Robert J. "Studies of noise in Josephson-effect mixers and their potential for submillimeter heterodyne detection." Thesis, 1995. https://thesis.library.caltech.edu/4221/1/Schoelkopf_rj_1995.pdf.

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NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. This thesis describes both theoretical and experimental investigations into the dynamics and noise processes of Josephson junctions, with the intent of evaluating their potential as mixers in heterodyne instruments for submillimeter-wave (i.e., the frequency range from 300 GHz to 3THz) detection. Superconducting tunnel junctions utilizing the nonlinearity due to photon-assisted tunneling of quasiparticles (SIS mixers) have become the state-of-the-art technology for sensitive heterodyne detection up to frequencies of about 700 [...]. Recent progress in the fabrication of high [...], superconductors has led to Josephson-effect devices with [...] products of up to ten millivolts, which might be suitable for mixing at frequencies of many terahertz. The key question for weighing the prospects for high-frequency Josephson mixers is that of the sensitivity which can be attained. Previous experimental work on Josephson mixing suggests the existence of an "excess" noise, which degrades the sensitivity. Theoretical modeling of mixer performance, based on the resistivelyshunted junction (RSJ) model for the dynamics of the device, also indicates the presence of larger noise than expected. The origin of this noise was not clearly understood, however, nor was its exact magnitude or expected scaling with frequency or junction characteristics known. In addition, previous experiments utilized crude devices of the point-contact type, which were unstable and thus undesirable for real applications. In the first part of this thesis research, extensive numerical simulations were performed with the RSJ model, including calculations of mixer noise and conversion efficiency. These calculations have revealed that the source of excess noise is the AC Josephson oscillations of the device, which can be completely incoherent, with a linewidth comparable to their frequency. Thus they appear as a broadband noise source. While this noise is intrinsic and unavoidable, an optimized mixer is still shown to be capable of interesting sensitivity levels, and the excess noise is expected to become relatively less important as the operating frequency is increased. Secondly, a process has been developed for the fabrication of stable, well-characterized, and reproducible Josephson devices based on resistively-shunted Nb and NbN tunnel junctions. The devices utilize submicron-area, high current-density tunnel junctions and a AuGe shunt resistor to yield completely non-hysteretic I-V curves, normal-state resistances of about [...] products of about half a millivolt. These devices should be nearly optimal for mixing at [...]. Heterodyne measurements using these junctions have been performed in a waveguide mixer mount. Receiver temperatures as low as 190 K (DSB), with -6 dB conversion efficiency, have been obtained at 100 [...], but these results are still a factor of about four higher than those predicted by the RSJ simulations. Accurate measurements of the available noise power of the junctions at the intermediate frequency of 1.5 [...] were made, and confirmed that the receivers were limited by elevated junction output noise. The deviations of the noise from theoretical predictions are shown to be caused by the nonlinear interaction of the junction with the embedding circuit. While this work points out some of the complexity introduced by the strong nonlinearity of Josephson devices, it is still expected that Josephson-effect mixers may be useful for heterodyne detection at very high frequencies.
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Частини книг з теми "Heterodyne effect":

1

Humbert, Laurent, Valéry Valle, and Mario Cottron. "Identification of Three-dimensional Effects in Cracked Plates from Quasi-heterodyne Interferometry." In Interferometry in Speckle Light, 527–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-642-57323-1_65.

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2

Mlynek, J., Chr Tamm, E. Buhr, and W. Lange. "Raman Heterodyne Detection of Radio-Frequency Resonances in Sm Vapor: Effects of Velocity-Changing Collisions." In Springer Series in Optical Sciences, 100–101. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-540-39664-2_27.

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3

"HETERODYNED KERR EFFECT MEASUREMENTS." In Handbook of Nonlinear Optics, 682–90. CRC Press, 2003. http://dx.doi.org/10.1201/9780203912539-18.

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4

Sutton, B. D., J. W. Ferguson, C. Pryer, E. Price, and D. Thomas. "Application of Continuous Velocity of Detonation Diagnostics to PE4 Cylinder Tests." In Future Developments in Explosives and Energetics, 135–47. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781839162350-00135.

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Velocity of detonation (VoD) is an important and often measured parameter for characterising explosive materials. This is traditionally measured using discrete time of arrival probes; time of arrival is plotted against position and a line of best fit used to find the VoD. This necessitates the use of a large amount of explosive material to allow steady state detonation to be reached prior to taking the measurement and provides no information on detonation propagation prior to this state being reached. A continuous method of measuring the VoD would allow smaller sample sizes to be used and would provide data from initiation through to steady state detonation. One diagnostic technique which has the potential to provide such continuous VoD measurements uses fibre Bragg gratings (FBGs). To assess their suitability, FBGs were tested on a series of PE4 cylinder tests. Cylinder tests are a commonly used characterisation test from which the expansion of the cylinder wall is also measured, thus it was also important to confirm that the presence of a FBG did not affect the expansion. Two types of gratings, uniform and chirped, were tested and the results compared to the traditional diagnostics. The measured detonation velocities are consistent with those obtained using the traditional electrical contact probes, and the effect the fibres have on the expansion of the copper cylinder has been assessed using heterodyne velocimetry and a high-speed framing camera and confirmed to be negligible. This shows that FBGs are a suitable replacement for, and improvement on, traditional diagnostics.
5

Sutton, B. D., J. W. Ferguson, C. Pryer, E. Price, and D. Thomas. "Application of Continuous Velocity of Detonation Diagnostics to PE4 Cylinder Tests." In Future Developments in Explosives and Energetics, 135–47. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/9781788017855-00135.

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Velocity of detonation (VoD) is an important and often measured parameter for characterising explosive materials. This is traditionally measured using discrete time of arrival probes; time of arrival is plotted against position and a line of best fit used to find the VoD. This necessitates the use of a large amount of explosive material to allow steady state detonation to be reached prior to taking the measurement and provides no information on detonation propagation prior to this state being reached. A continuous method of measuring the VoD would allow smaller sample sizes to be used and would provide data from initiation through to steady state detonation. One diagnostic technique which has the potential to provide such continuous VoD measurements uses fibre Bragg gratings (FBGs). To assess their suitability, FBGs were tested on a series of PE4 cylinder tests. Cylinder tests are a commonly used characterisation test from which the expansion of the cylinder wall is also measured, thus it was also important to confirm that the presence of a FBG did not affect the expansion. Two types of gratings, uniform and chirped, were tested and the results compared to the traditional diagnostics. The measured detonation velocities are consistent with those obtained using the traditional electrical contact probes, and the effect the fibres have on the expansion of the copper cylinder has been assessed using heterodyne velocimetry and a high-speed framing camera and confirmed to be negligible. This shows that FBGs are a suitable replacement for, and improvement on, traditional diagnostics.

Тези доповідей конференцій з теми "Heterodyne effect":

1

Manriquez, Jose Soto. "Phase matching memory effect in optical coherent transient effects." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.thjj5.

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It has been generally accepted that the off-resonance heterodyne optical field in Stark-switching and frequency-switching techniques does not have any measurable influence in photon echo and other related experiments. In this work we present theoretical and experimental evidence that through a previously unknown memory effect the heterodyne field produces important undulations in the decay curves of photon echo. This effect appears to be also responsible for other experimental anomalies observed in optical coherent transient effects.1
2

Iftekharuddin, K. M., and M. A. Karim. "Effect of background radiation noise on heterodyne detection efficiency in the use of a diffraction-free beam." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.thv3.

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Several experiments have been carried out to maximize optical heterodyne efficiency when the Gaussian laser beam is used as the signal field.1 Further, it has already been shown that heterodyne efficiency is significantly improved with the use of the diffraction-free Bessel beam in the absence of noise.2 However, for most of the small signal detection schemes, background radiation noise is known to limit the achievable SNR. In our present work we consider background noise effect on the maximum heterodyne efficiency when the Bessel beam is used as the signal, and we accordingly investigate the tilt and offset effect of the incoming signal.
3

Zhengfang, Song, Gu Weiyu, and Liu Xiachun. "The Optical Heterodyne Detection in a Turbulent Atmosphere." In Optical Remote Sensing. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/ors.1985.tuc3.

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It is well-known that atmospheric turbulence has a serious effect on optical heterodyne detection. However, the effect of the turbulent outer scale up to date has not an acknowledged view yet. Lutomirski and Yura [1] considered that the presence of a definite outer scale could increase the signal-to-noise ratio of heterodyne detection slightly. Clifford and Wandzura [2] indicated that the performance of a heterodyne lidar could be deteriorated with the outer scale. So it is still intrested to clarify the real action of the outer scale.
4

Di Gaspare, Alessandra, Valeria Giliberti, Roberto Casini, Ennio Giovine, Florestanto Evangelisti, Dominique Coquillat, Wojciech Knap, et al. "Antenna-coupled heterostructure field effect transistors for integrated terahertz heterodyne mixers." In SPIE OPTO, edited by Laurence P. Sadwick and Créidhe M. O'Sullivan. SPIE, 2013. http://dx.doi.org/10.1117/12.2004087.

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5

Marinchio, H., C. Palermo, G. Sabatini, P. Ziade, P. Shiktorov, E. Starikov, V. Gruzinskis, et al. "Hydrodynamic simulation of heterodyne terahertz detection in a field effect transistor." In 2010 35th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2010). IEEE, 2010. http://dx.doi.org/10.1109/icimw.2010.5612505.

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6

Yan, Zhifeng, Jingxuan Zhu, Xinnan Lin, Frank He, Guozeng Wang, Zhang Yang, and Juncheng Cao. "A generic numerical model on heterodyne terahertz detection in field effect transistor." In 2010 3rd International Congress on Image and Signal Processing (CISP). IEEE, 2010. http://dx.doi.org/10.1109/cisp.2010.5647135.

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7

Aoyama, Hajime, Fumiaki Kumasaka, Yoshihisa Iba, Takao Taguchi, Masayuki Takeda, Masaki Yamabe, Makoto Fukuda, Masanori Suzuki, and Kimiyoshi Deguchi. "Effect of SiC x-ray masks on alignment accuracy of heterodyne alignment." In Microlithography '97, edited by David E. Seeger. SPIE, 1997. http://dx.doi.org/10.1117/12.275796.

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8

Shani, Yosi, Rod Alferness, Tom Koch, Uzi Koren, Moshe Oron, Barry I. Miller, and Martin G. Young. "Polarization rotation in asymmetric periodic loaded rib waveguides." In Integrated Photonics Research. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/ipr.1991.thh3.

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Polarization rotation is an important effect in integrated optics. It is required in balanced polarization diversity heterodyne receivers and in polarization controllers. Polarization rotation has been demonstrated in LiNbO3 and in III-V waveguides using the electro-optic effect1−3 and LiNbO3 using the photo-elastic effect.4
9

Thantu, Napoleon. "Time-resolved optical heterodyne detected raman induced kerr effect spectroscopy for chemical analyis." In Laser Applications to Chemical and Environmental Analysis. Washington, D.C.: OSA, 2001. http://dx.doi.org/10.1364/lacea.2000.pd5.

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10

Liu, Yarui, Su'an Xu, Yaqiong Fu, Fei Qian, and Feng Zhang. "Effect of nonlinearity by polarization beam splitter in the double passage heterodyne interferometer." In Seventh International Symposium on Precision Mechanical Measurements, edited by Liandong Yu. SPIE, 2016. http://dx.doi.org/10.1117/12.2214616.

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Звіти організацій з теми "Heterodyne effect":

1

Mercer, Linden B. 1/F Frequency Noise Effects on Self-Heterodyne Linewidth Measurements for Coherent Communications. Fort Belvoir, VA: Defense Technical Information Center, July 1990. http://dx.doi.org/10.21236/ada227942.

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