Bibliographies thématiques / Spectral purity transfer

Littérature scientifique sur le sujet « Spectral purity transfer »

Auteur : Grafiati
Publié le 14 mars 2023

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Articles de revues sur le sujet "Spectral purity transfer"

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Nicolodi, Daniele, Bérengère Argence, Wei Zhang, Rodolphe Le Targat, Giorgio Santarelli et Yann Le Coq. « Spectral purity transfer between optical wavelengths at the 10−18 level ». Nature Photonics 8, no 3 (19 janvier 2014) : 219–23. http://dx.doi.org/10.1038/nphoton.2013.361.

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Xue, Hang, Yang Yang, Xiping Xu, Ning Zhang et Yaowen Lv. « Application of Near Infrared Hyperspectral Imaging Technology in Purity Detection of Hybrid Maize ». Applied Sciences 13, no 6 (9 mars 2023) : 3507. http://dx.doi.org/10.3390/app13063507.

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Seed purity has an important impact on the yield and quality of maize. Studying the spectral characteristics of hybrid maize and exploring the rapid and non-destructive detection method of seed purity are conducive to the development of maize seed breeding and planting industry. The near-infrared spectral data of five hybrid maize seeds were collected in the laboratory. After eliminating the obvious noises, the multiple scattering correction (MSC) was applied to pretreat the spectra. PLS-DA, KNN, NB, RF, SVM-Linear, SVM-Polynomial, SVM-RBF, and SVM-Sigmaid were used as pattern recognition methods to classify five different types of maize seeds. The recognition accuracy of the models established by different algorithms was 84.4%, 97.6, 100%, 96.4, 99.2%, 100%, 98.4%, and 91.2%, respectively. The results indicated that hyperspectral imaging technology could be used for variety classification and the purity detection of maize seeds. To improve the calculation speed, using the principal component analysis (PCA) to reduce the dimension of hyperspectral data, we then established classification models based on characteristic wavelengths. The recognition accuracy of the models established by different algorithms was 80.8%, 86.8%, 98%, 94%, 96.8%, 98.4%, 94.4%, and 88.2%, respectively. The results showed that the selected sensitive wavelengths could be used to detect the purity of maize seeds. The overall results indicated that it was feasible to use near-infrared hyperspectral imaging technology for the variety identification and purity detection of maize seeds. This study also provides a new method for rapid and non-destructive detection of seed purity.
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Park, Kyungdeuk, Dongjin Lee et Heedeuk Shin. « Tunability of the Nonlinear Interferometer Method for Anchoring Constructive Interference Patterns on the ITU-T Grid ». Applied Sciences 11, no 4 (5 février 2021) : 1429. http://dx.doi.org/10.3390/app11041429.

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Recently, a method of engineering the quantum states with a nonlinear interferometer was proposed to achieve precise state engineering for near-ideal single-mode operation and near-unity efficiency (L. Cui et al., Phys. Rev. A 102, 033718 (2020)), and the high-purity bi-photon states can be created without degrading brightness and collection efficiency. Here, we study the coarse or fine tunability of the nonlinear interference method to match constructive interference patterns into a transmission window of standard 100-GHz DWDM channels. The joint spectral intensity spectrum is measured for various conditions of the nonlinear interference effects. We show that the method has coarse- and fine-tuning ability while maintaining its high spectral purity. We expect that our results expand the usefulness of the nonlinear interference method. The photon-pair generation engineered via this method will be an excellent practical source of the quantum information process.
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Barbieri, Piero, Cecilia Clivati, Marco Pizzocaro, Filippo Levi et Davide Calonico. « Spectral purity transfer with 5 × 10−17 instability at 1 s using a multibranch Er:fiber frequency comb ». Metrologia 56, no 4 (5 juillet 2019) : 045008. http://dx.doi.org/10.1088/1681-7575/ab2b0f.

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Lin, Zhong-Ping, et Walter A. Aue. « Gas-phase luminescence of aromatic carbonyl compounds in excited nitrogen at atmospheric pressure ». Canadian Journal of Chemistry 78, no 1 (15 janvier 2000) : 95–117. http://dx.doi.org/10.1139/v99-203.

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Certain types of aroyl compounds such as benzaldehyde, acetophenone, benzophenone, and anthraquinone produce intense gas-phase luminescence in excited nitrogen at atmospheric pressure. This luminescence was measured in pressure ranges of 1.00–1.67 atm and temperature ranges of 343–473 K. A novel, radioactively (Ni-63) stimulated, high-voltage( [Formula: see text]1750 V/mm), low-current ( [Formula: see text]35 nA) discharge in high-purity nitrogen was used for gas chromatographic detection and spectral excitation. The gas-phase luminescence spectra of about sixty aroyl compounds - introduced as gas chromatographic peaks - could thus be measured and compared with literature spectra obtained by conventional excitation in condensed phases. Only a few gas-phase spectra are available from the literature, and these did agree well with the spectra of this study. A speculative luminescence mechanism is proposed, in which ground-state N2 becomes excited by collision with fast electrons. This is followed by efficient triplet-triplet energy transfer from N2(A 3Σu+) to the n–>π* excited aroyl compound. Key words: aroyl phosphorescence, excited-nitrogen excitation, aroyl triplet-triplet excitation, aroyl luminescence detection, gas-phase phosphorescence spectra, gas-phase aroyl detection.
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Kim, Ilhwan, Donghwa Lee et Kwang Jo Lee. « Numerical Investigation of High-Purity Polarization-Entangled Photon-Pair Generation in Non-Poled KTP Isomorphs ». Applied Sciences 11, no 2 (8 janvier 2021) : 565. http://dx.doi.org/10.3390/app11020565.

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We investigated the high-purity entangled photon-pair generation in five kinds of “non-poled” potassium titanyl phosphate (KTP) isomorphs (i.e., KTiOPO4, RbTiOPO4, KTiOAsO4, RbTiOAsO4, and CsTiOAsO4). The technique is based on the spontaneous parametric down-conversion (SPDC) under Type II extended phase matching (EPM), where the phase matching and the group velocity matching are simultaneously achieved between the interacting photons in non-poled crystals rather than periodically poled (PP) KTPs that are widely used for quantum experiments. We discussed both theoretically and numerically all aspects required to generate photon pairs in non-poled KTP isomorphs, in terms of the range of the beam propagation direction (or the spectral range of photons) and the corresponding effective nonlinearities and beam walk-offs. We showed that the SPDC efficiency can be increased in non-poled KTP isomorphs by 29% to 77% compared to PPKTP cases. The joint spectral analyses showed that photon pairs can be generated with high purities of 0.995–0.997 with proper pump filtering. In contrast to the PPKTP case, where the EPM is achieved only at one specific wavelength, the spectral position of photon pairs in the non-poled KTP isomorphs can be chosen over the wide range of 1883.8–2068.1 nm.
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Zhang, Xiangyue, Yueming Wang et Tianru Xue. « Quadratic Clustering-Based Simplex Volume Maximization for Hyperspectral Endmember Extraction ». Applied Sciences 12, no 14 (15 juillet 2022) : 7132. http://dx.doi.org/10.3390/app12147132.

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The existence of intra-class spectral variability caused by differential scene components and illumination conditions limits the improvement of endmember extraction accuracy, as most endmember extraction algorithms directly find pixels in the hyperspectral image as endmembers. This paper develops a quadratic clustering-based simplex volume maximization (CSVM) approach to effectively alleviate spectral variability and extract endmembers. CSVM first adopts spatial clustering based on simple linear iterative clustering to obtain a set of homogeneous partitions and uses spectral purity analysis to choose pure pixels. The average of the chosen pixels in each partition is taken as a representative endmember, which reduces the effect of local-scope spectral variability. Then an improved spectral clustering based on k-means is implemented to merge homologous representative endmembers to further reduce the effect of large-scope spectral variability, and final endmember collection is determined by the simplex with maximum volume. Experimental results show that CSVM reduces the average spectral angle distance on Samson, Jasper Ridge and Cuprite datasets to below 0.02, 0.06 and 0.09, respectively, provides the root mean square errors of abundance maps on Samson and Jasper Ridge datasets below 0.25 and 0.10, and exhibits good noise robustness. By contrast, CSVM provides better results than other state-of-the-art algorithms.
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Ou, Yiyi, Junyu Wei et Hongbin Liang. « Tunable Luminescence and Energy Transfer of Sr3B2O6:Ce3+, Sm3+ Phosphors with Potential Anti-Counterfeiting Applications ». Materials 15, no 15 (26 juillet 2022) : 5189. http://dx.doi.org/10.3390/ma15155189.

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Sm3+ and Ce3+ singly doped and Sm3+ and Ce3+ co-doped Sr3B2O6 phosphors are prepared via a high-temperature solid-state reaction method. The crystal structure and phase purity are characterized by X-ray diffraction (XRD) analyses. The Sm3+-doped sample displays an emission in the orange-red region, with the strongest emission line at about 648 nm and possessing a good luminescence thermal stability between 78 and 500 K. With the increase in the Sm3+ content, the concentration quenching is observed due to the cross-relaxation (CR) processes among the Sm3+ ions. Upon 340 nm excitation, the Ce3+-doped phosphor presents a broad emission band in the blue region with a maximum at about 420 nm, which overlaps well with the 6H5/2 → 6P3/2 excitation line of Sm3+ and implies the possible energy transfer from Ce3+ to Sm3+. The spectral and decay measurements of the Ce3+ and Sm3+ co-doped samples are conducted and the Inokuti–Hirayama (I-H) model is adopted to analyze the luminescence decay dynamics of the donor Ce3+. Owing to the evident sensitization of the Sm3+ by the Ce3+ ions, the co-doped samples exhibit color variation under different wavelength excitations, endowing them with potential applications in optical anti-counterfeiting.
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Nejo, Adeola A., Gabriel A. Kolawole, Ayorinde O. Nejo, Tebogo V. Segapelo et Christo J. Muller. « Synthesis, Structural, and Insulin-Enhancing Studies of Oxovanadium(IV) Complexes ». Australian Journal of Chemistry 64, no 12 (2011) : 1574. http://dx.doi.org/10.1071/ch11291.

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Oxovanadium(iv) complexes with Schiff bases derived from substituted salicylaldehyde and diamine have been prepared and characterized. 1H NMR and IR spectral data revealed that the symmetrical Schiff base was isolated, and elemental analysis confirmed the purity of all the compounds as formulated. The room-temperature magnetic moments of 1.6–1.8 Bohr magneton for the complexes confirmed that the complexes are VIV complexes, with d1 configuration. Cyclic voltammetry revealed only one quasi-reversible wave for each complex and they all showed redox couples with peak-to-peak separation values (ΔEp) ranging from 76 to 84 mV, indicating a single-step one-electron transfer process. An oral administration of these complexes supplied at a dose of 0.2 mmol kg–1 to streptozotocin-induced diabetic rats elicited a progressive reduction in plasma glucose over 6-h periods. Two of the complexes produced significant and consistent reduction in fasting blood glucose levels over a 6-h monitoring period.
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D. Lakshmijayasimha, Prajwal D., Prince M. Anandarajah, Pascal Landais et Aleksandra Kaszubowska-Anandarajah. « Optical Frequency Comb Expansion Using Mutually Injection-Locked Gain-Switched Lasers ». Applied Sciences 11, no 15 (31 juillet 2021) : 7108. http://dx.doi.org/10.3390/app11157108.

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We propose a novel scheme for the expansion and comb densification of gain-switched optical frequency combs (GS-OFC). The technique entails mutual injection locking of two gain-switched lasers with a common master to generate a wider bandwidth OFC. Subsequently, the OFC is further expanded and/or densified using a phase modulator with optimum drive conditions. We experimentally demonstrate the generation of an OFC with 45 highly correlated lines separated by 6.25 GHz with an expansion factor ~3. In addition, operating in comb densification mode, the channel spacing of the OFC is tuned from 6.25 GHz to 390.625 MHz. Finally, a detailed characterization of the lines, across the entire expanded comb, is reported highlighting the excellent spectral purity with linewidths of ~40 kHz, a relative intensity noise better than –152 dB/Hz, and a high degree of phase correlation between the comb lines. The proposed method is simple, highly flexible and the architecture is suitable for photonic integration, all of which make such an OFC extremely attractive for the employment in a multitude of applications.
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Thèses sur le sujet "Spectral purity transfer"

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Lee, Wonchul. « Development of Raman and Thomson scattering diagnostics for study of energy transfer in nonequilibrium, molecular plasmas ». Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1054652829.

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Thesis (Ph. D.)--Ohio State University, 2003.
Title from first page of PDF file. Document formatted into pages; contains xvi, 210 p.; also includes graphics (some col.) Includes bibliographical references (p. 178-184). Available online via OhioLINK's ETD Center
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RAUF, BENJAMIN. « Absolute frequency measurement of an 171Yb lattice clock and optical clock comparisons ». Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2708557.

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The measurement of time and frequency is at the heart of many technological applications and scientific measurements alike. In fact, the SI-unit the second is by quite a margin the SI-unit with the best relative uncertainty (ca. 10^{-16}), given by the accuracies of Cs fountain clocks probing the F = 3 - F = 4 ground-state transition in 133Cs. Still, demands for even higher accuracy and especially stability (a Cs fountain needs up to two weeks for the statistics to reach its declared uncertainty) are uttered in support of technological advancements (e.g. geodesy and GNSS systems) as well as fundamental science (physics beyond the standard model, tests of relativity). Nowadays optical lattice clocks confining a large number of neutral atoms in Stark shift free optical traps (the Stark shift free condition is characterised by a so-called magic wavelength of the trap) propose good candidates for a future redefinition of the SI-second in terms of an optical transition. Their accuracy and stability already surpass the Cs-fountains by two and three orders of magnitude, respectively. With further improvements to be expected in the near future, the application of optical lattice clocks to relativistic gravimetry, quantum computing, quantum simulation and fundamental physics keeps evolving. This thesis describes the development and characterisation of an 171Yb lattice clock at INRIM as well as its first frequency measurement campaigns and technolo- gies towards improved optical frequency measurements. The lattice clock confines cold atoms in a 1D optical dipole trap at the magic wavelength, which also cancels any Doppler- and recoil-related effects on the ultra-narrow clock transition. The first chapter offers a general overview of the physics behind lattice clocks and opti- cal frequency measurements. In the second chapter the 171Yb lattice clock developed during this work is expounded, including the trapping, state-preparation and state-probing of ultracold atoms inside the optical lattice. An exhaustive uncertainty budget for the clock transition is given and discussed showing already a performance beyond state-of- the-art Cs fountain clocks. An absolute frequency measurement obtained during this work is laid out. The result represents the lowest uncertainty achieved in a measurement of this transition against a primary frequency standard so far and is in agreement with previous values obtained by other groups around the world. A proof-of-principle experiment demonstrating for the first time the feasibility of transportable optical lattice clocks for geodesy and metrology applications outside of laboratory environments is described in chapter three. This experiment was conducted in collaboration with PTB and NPL and included a geodetic measurement with a transportable optical lattice clock that agreed with conventional methods as well as an optical 171Yb-87Sr frequency ratio measurement, enlarging the database on this particular ratio and thereby contributing to a possible redefinition of the SI-unit the second in terms of an optical transition or frequency-ratio matrix in the future. The fourth chapter discusses improvements added to the Yb lattice clock after the aforementioned measurements, in particular the stabilisation of the cooling and trapping lasers on a single stable low-drift cavity using mirrors coated for three disparate wavelengths across the optical spectrum. The simultaneous offset sideband locking and a throughout characterisation of the cavity are discussed. The last chapter is about the characterisation and optimisation of the NPL universal oscillator, which was conducted during my secondment at the NPL research facilities in the UK. The universal oscillator consists out of a femtosecond frequency comb, an ultra stable master laser and six slave oscillators. The femtosecond comb is transferring the stability of the superior master oscillator cavity to all six slave oscillators, which includes five lasers ranging from the infrared to the visible region. The principle of operation is explained and the obtained high performance of the spectral purity transfer set forth and discussed. This experiment demonstrated an unprecedented spectral purity transfer performance in a multi-branch configuration, opening the way for the interrogation of whole clock ensembles by just one master oscillator.
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Actes de conférences sur le sujet "Spectral purity transfer"

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Giunta, M., W. Hansel, M. Lezius, M. Fischer, Ronald Holzwarth, E. Benkler, D. Matei, T. Legero et Uwe Sterr. « Spectral Purity Transfer for High Performance Strontium Lattice Clocks ». Dans 2018 IEEE International Frequency Control Symposium (IFCS). IEEE, 2018. http://dx.doi.org/10.1109/fcs.2018.8597528.

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Giunta, M., W. Hänsel, M. Lezius, M. Fischer et R. Holzwarth. « Sub-mHz Spectral Purity Transfer for Next Generation Strontium Optical Atomic Clocks ». Dans CLEO : Science and Innovations. Washington, D.C. : OSA, 2018. http://dx.doi.org/10.1364/cleo_si.2018.sm1l.5.

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Alvarez-Martinez, Hector, Christian Barentsen, Yann Le Coq et Rodolphe Le Targat. « Transfer of Spectral Purity Between Four Wavelengths at the 10-8 Level ». Dans 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC). IEEE, 2019. http://dx.doi.org/10.1109/fcs.2019.8856135.

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Nicolodi, Daniele, Berengere Argence, Wei Zhang, Rodolphe Le Targat, Giorgio Santarelli et Yann Le Coq. « Spectral purity transfer between optical wavelengths at the 10−18 level ». Dans 2014 Conference on Precision Electromagnetic Measurements (CPEM 2014). IEEE, 2014. http://dx.doi.org/10.1109/cpem.2014.6898260.

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Zou, P., M. Giunta, W. Hänsel, M. Lezius, M. Fischer et R. Holzwarth. « Sub-Hz Spectral Purity Transfer at the 10–18 level based on optical frequency comb ». Dans Conference on Lasers and Electro-Optics/Pacific Rim. Washington, D.C. : OSA, 2018. http://dx.doi.org/10.1364/cleopr.2018.w2f.6.

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Yann, LeCoq. « Novel techniques for low-noise microwave generation and transfer of spectral purity with optical frequency combs ». Dans 2014 IEEE International Frequency Control Symposium (FCS). IEEE, 2014. http://dx.doi.org/10.1109/fcs.2014.6859852.

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Giunta, M., W. Hansel, M. Fischer, M. Lezius et R. Holzwarth. « Simultaneous spectral purity transfer at three optical clock transitions using an ultra-low noise Er:Fiber frequency comb ». Dans 2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium ((EFTF/IFC). IEEE, 2017. http://dx.doi.org/10.1109/fcs.2017.8089032.

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Teodorescu, George, Peter D. Jones, Ruel A. Overfelt et Baojian Guo. « Spectral-Directional Emittance of High Temperature Oxidized Aluminum ». Dans ASME 2005 Summer Heat Transfer Conference collocated with the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems. ASMEDC, 2005. http://dx.doi.org/10.1115/ht2005-72828.

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Spectral-directional emittance measurements for high purity aluminum, oxidized in air for an extended period of time (150h) at high temperature are presented. The data presented here cover the spectral range between 3 and 14 μm, directional range from surface normal to 72° polar angle and temperatures from 400 to 600°C with a step increment of 100°C. The measurements were performed using a radiometric, direct emission method. The experimental setup used was comprised of a Fourier transform infrared spectrometer and a blackbody cavity. The Al sample has a nominal surface roughness of 0.635 μm. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used as surface techniques to characterize the aluminum oxide film that formed on the metallic surface.
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Brekenfeld, Manuel, Benjamin Rauf, Sarah Saint-Jalm, Garrett D. Cole, Gar-Wing Truong, Maurice Lessing, Andreas Fricke, Marc Fischer, Michele Giunta et Ronald Holzwarth. « Rack-Mounted Ultrastable Laser System for Sr Lattice Clock Operation ». Dans CLEO : Science and Innovations. Washington, D.C. : Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleo_si.2022.stu5o.7.

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We present a rack-mounted ultra-low-noise laser system for Sr lattice clocks, with spectral purity transfer stability of 4×10−18@1s and 2×10−19@100s. We realize a system stability of 5×10-16@1s, representing state-of-the-art performance for rack-mounted commercial systems.
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Cameron, Seth A., et Michael G. Littman. « Quantum fluctuations in a singlemode pulsed dye laser ». Dans OSA Annual Meeting. Washington, D.C. : Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.wl6.

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We have studied the intensity fluctuations from a pulsed single-mode grazing incidence dye laser. The laser operates using rhodamine 6G dye pumped by 308-nm radiation from a XeCl excimer laser. Pump laser pulse duration is 6-8 ns and dye laser pulse duration is 2-3 ns. The spectral purity of the dye laser radiation is within 20% of the Fourier transform limit. Using event-mode recording involving the monitoring of pump laser intensity and dye laser intensity, we have determined the amplitude distribution from the dye laser at pumping conditions below, slightly above, and significantly above threshold. The amplitude fluctuations from the dye laser are well characterized by a Fokker-Planck model and they appear to be quantum in origin.
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Rapports d'organisations sur le sujet "Spectral purity transfer"

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Barefoot, Susan, Benjamin Juven, Thomas Hughes, Avraham Lalazar, A. B. Bodine, Yitzhak Ittah et Bonita Glatz. Characterization of Bacteriocins Produced by Food Bioprocessing Propionobacteria. United States Department of Agriculture, août 1992. http://dx.doi.org/10.32747/1992.7561061.bard.

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Objectives were to further characterize activity spectra of dairy propionibacteria bacteriocins, jenseniin G and propionicin PLG-1, purify them, examine the role of cell walls in resistance, examine their interactions with cytoplasmic membrane, explain producer immunity, and clone the responsible genes. Inhibitory spectra of both bacteriocins were further characterized. Propionicin was most effective in controlling Gram-positive, rather than Gram-negative organisms; it controlled growth of sensitive cells both in a culture medium and a model food system. Jenseniin inhibited yogurt cultures and may help prevent yogurt over-acidification. Both were active against botulinal spores; jenseniin was sporostatic; propionicin was sporicidal. Jenseniin was produced in broth culture, was stable to pH and temperature extremes, and was purified. Its molecular mass (3649 Da) and partial amino acid composition (74%) were determined. A blocked jenseniin N-terminus prevented sequencing. Methods to produce propionicin in liquid culture were improved, and large scale culture protocols to yield high titers were developed. Methods to detect and quantify propionicin activity were optimized and standardized. Stability of partially purified propionicin was demonstrated and an improved purification scheme was developed. Purified propionicin had a 9328-Da molecular mass, contained 99 amino acids, and was significantly hydrophobic; ten N-terminal amino acids were identified. Propionicin and Jenseniin interacted with cytoplasmic membranes; resistance of insensitive species was cell wall-related. Propionicin and jenseniin acted similarly; their mode of action appeared to differ from nisin. Spontaneous jenseniin-resistant mutants were resistant to propionicin but nisin-sensitive. The basis for producer immunity was not resolved. Although bacteriocin genes were not cloned, a jenseniin producer DNA clone bank and three possible vectors for cloning genes in propionibacteria were constructed. In addition, transposon Tn916 was conjugatively transferred to the propionicin producer from chromosomal and plasmid locations at transfer frequencies high enough to permit use of Tn916 for insertional mutagenesis or targeting genes in propionibacteria. The results provide information about the bacteriocins that further supports their usefulness as adjuncts to increase food safety and/or quality.
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