The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Stuart D. Jackson - One of the best experts on this subject based on the ideXlab platform.
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Mode-locked and tunable fiber laser at the 35 µm band using frequency-shifted feedback
Optics Letters, 2019Co-Authors: Ori Henderson-sapir, Matthew R. Majewski, Robert I. Woodward, Nathaniel Bawden, David J. Ottaway, Stuart D. JacksonAbstract:We report on a mid-infrared mode-locked fiber laser that uses an acousto-optic tunable filter to achieve frequency-shifted feedback pulse generation with frequency tuning over a 215 nm range. The laser operates on the 3.5 µm transition in erbium-doped zirconium fluoride-based fiber and utilizes the dual-Wavelength pumping scheme. Stable, self-starting mode locking with a minimum pulse duration of 53 ps was measured using a two-photon absorption autocorrelator. The Longest Wavelength demonstrated was 3612 nm, and the maximum average powers achieved were 50 and 167 mW in fundamental and multi-pulse mode-locking regimes, respectively. To the best of our knowledge, this is the Longest Wavelength rare-earth-doped mode-locked fiber laser demonstrated. The broad tunability promises potential uses for environmental sensing applications.
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Mode-locked and tunable fiber laser at the 3.5 ${\mu}$m band using frequency-shifted feedback
arXiv: Optics, 2019Co-Authors: Ori Henderson-sapir, Matthew R. Majewski, Nathaniel Bawden, R. I. Woodward, David J. Ottaway, Stuart D. JacksonAbstract:We report on a mid-infrared mode-locked fiber laser that uses an acousto-optic tunable filter to achieve frequency-shifted feedback pulse generation with frequency tuning over a 215 nm range. The laser operates on the 3.5 ${\mu}$m transition in erbium-doped zirconium fluoride-based fiber and utilizes the dual-Wavelength pumping scheme. Stable, self-starting mode-locking with a minimum pulse duration of 53 ps was measured using a two-photon absorption autocorrelator. The Longest Wavelength demonstrated was 3612 nm and a maximum average power of 208 mW was achieved. This is the Longest Wavelength rare-earth doped mode-locked fiber laser demonstrated to the best of the authors' knowledge. The broad tunability promises potential uses for environmental sensing applications.
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Emission Beyond 4 μm and Mid-infrared Lasing from a Dy 3+ :InF 3 Fiber
Conference on Lasers and Electro-Optics, 2018Co-Authors: Matthew R. Majewski, Robert I. Woodward, Jean-yves Carrée, Samuel Poulain, Marcel Poulain, Stuart D. JacksonAbstract:We present a dysprosium-doped InF 3 fiber exhibiting emission beyond 4 microns; the Longest Wavelength to date from a fluoride-based fiber. Laser emission around 3 μm is also demonstrated.
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Versatile Mid-Infrared Mode-Locked Fiber Laser, Electronically Tunable from 2.97 to 3.30 μm
CLEO Pacific Rim Conference, 2018Co-Authors: Robert I. Woodward, Matthew R. Majewski, Stuart D. JacksonAbstract:We demonstrate the first dysprosium mode-locked laser: the Longest Wavelength and most widely tunable mode-locked fiber laser to date. Picosecond pulses are generated by a novel frequency-shifted feedback mechanism using an intracavity acousto-optic tunable filter.
Jochen Autschbach - One of the best experts on this subject based on the ideXlab platform.
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Longest-Wavelength Electronic Excitations of Linear Cyanines: The Role of Electron Delocalization and of Approximations in Time-Dependent Density Functional Theory.
Journal of chemical theory and computation, 2013Co-Authors: Barry Moore, Jochen AutschbachAbstract:The lowest-energy/Longest-Wavelength electronic singlet excitation energies of linear cyanine dyes are examined, using time-dependent density functional theory (TDDFT) and selected wave function methods in comparison with literature data. Variations of the bond-length alternation obtained with different optimized structures produce small differences of the excitation energy in the limit of an infinite chain. Hybrid functionals with range-separated exchange are optimally ‘tuned’, which is shown to minimize the delocalization error (DE) in the cyanine π systems. Much unlike the case of charge-transfer excitations, small DEs are not strongly correlated with better performance. A representative cyanine is analyzed in detail. Compared with accurate benchmark data, TDDFT with ‘pure’ local functionals gives too high singlet excitation energies for all systems, but DFT-based ΔSCF calculations with a local functional severely underestimates the energies. TDDFT strongly overestimates the difference between singlet ...
Arnd Vogler - One of the best experts on this subject based on the ideXlab platform.
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Photoluminescence of PtII(cyclooctatetraene)(CN)2 originating from a MLCT triplet
Inorganic Chemistry Communications, 2006Co-Authors: Horst Kunkely, Arnd VoglerAbstract:Abstract The complex PtII(cyclooctatetraene)(CN)2 shows a Longest-Wavelength absorption (λmax = 430 nm) which is assigned to a (PtII → π∗ C8H8) MLCT transition. At r.t. the solid complex displays an intense orange emission at 572 nm which originates from the MLCT triplet. The emission spectrum exhibits a vibrational structure which may indicate an IL contribution.
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Photolysis of tetraphenylcyclobutadiene palladium chloride induced by LMCT excitation
Inorganic Chemistry Communications, 2006Co-Authors: Horst Kunkely, Arnd VoglerAbstract:Abstract The complex tetraphenylcyclobutadiene palladium(IV) chloride shows a Longest-Wavelength absorption at λ max = 530 nm which is assigned to a LMCT transition from the C 4 Ph 4 dianion to Pd(IV). LMCT excitation leads to the release of Pd(CH 3 CN) 2 Cl 2 and neutral C 4 Ph 4 which dimerizes to octaphenylcyclooctatetraene.
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Photoreactivity and Photoluminescence of Aluminum Maltolate
Zeitschrift für Naturforschung B, 2005Co-Authors: Horst Kunkely, Arnd VoglerAbstract:Aluminium maltolate shows a Longest-Wavelength absorption at λ m a x = 314 nm which is of the intraligand (IL) type. IL excitation leads to a photodecomposition of the ligand (Φ = 0.04 at λ i r r = 313 nm, in ethanol). While a fluorescence is not observed, Al maltolate displays a phosphorescence in low-temperature glasses (λ m a x = 510 nm at 77 K, in ethanol).
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Photochemistry of trichloro(phenylazo)bis(triphenylphosphine)ruthenium(II) induced by Ru to phenyldiazonium MLCT excitation
Inorganic Chemistry Communications, 2005Co-Authors: Horst Kunkely, Arnd VoglerAbstract:Abstract The complex trichloro(phenylazo)bis(triphenylphosphine)ruthenium(II) shows a Longest-Wavelength absorption at λmax = 520 nm which is assigned to a Ru(II) → phenyldiazonium+ MLCT transition. MLCT excitation leads to the oxidation of the metal and reduction of the diazonium cation which decays to nitrogen and phenyl radical.
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Excited state properties of dimeric π-allylpalladium(II) chloride.
Inorganica Chimica Acta, 2003Co-Authors: Horst Kunkely, Arnd VoglerAbstract:Abstract The Longest-Wavelength absorption of [(π-allyl)PdIICl]2 at λmax=318 nm is assigned to an allyl−→PdII ligand-to-metal charge transfer (LMCT) transition. In the primary photochemical step LMCT excitation leads to the formation of an allyl radical and PdICl, which in acetonitrile undergoes a disproportionation to metallic palladium and palladium(II). PdII(CH3CN)2Cl2 is formed with φ=0.008 at λirr=366 nm.
Miquel Huix-rotllant - One of the best experts on this subject based on the ideXlab platform.
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Assessment of density functional theory based ΔSCF (self-consistent field) and linear response methods for Longest Wavelength excited states of extended π-conjugated molecular systems
The Journal of chemical physics, 2014Co-Authors: Michael Filatov, Miquel Huix-rotllantAbstract:Computational investigation of the Longest Wavelength excitations in a series of cyanines and linear n-acenes is undertaken with the use of standard spin-conserving linear response time-dependent density functional theory (TD-DFT) as well as its spin-flip variant and a ΔSCF method based on the ensemble DFT. The spin-conserving linear response TD-DFT fails to accurately reproduce the lowest excitation energy in these π-conjugated systems by strongly overestimating the excitation energies of cyanines and underestimating the excitation energies of n-acenes. The spin-flip TD-DFT is capable of correcting the underestimation of excitation energies of n-acenes by bringing in the non-dynamic electron correlation into the ground state; however, it does not fully correct for the overestimation of the excitation energies of cyanines, for which the non-dynamic correlation does not seem to play a role. The ensemble DFT method employed in this work is capable of correcting for the effect of missing non-dynamic correlation in the ground state of n-acenes and for the deficient description of differential correlation effects between the ground and excited states of cyanines and yields the excitation energies of both types of extended π-conjugated systems with the accuracy matching high-level ab initio multireference calculations.
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Assessment of density functional theory based Delta SCF (self-consistent field) and linear response methods for Longest Wavelength excited states of extended pi-conjugated molecular systems
Journal of Chemical Physics, 2014Co-Authors: Michael Filatov, Miquel Huix-rotllantAbstract:Computational investigation of the Longest Wavelength excitations in a series of cyanines and linear n-acenes is undertaken with the use of standard spin-conserving linear response time-dependent density functional theory (TD-DFT) as well as its spin-flip variant and a Delta SCF method based on the ensemble DFT. The spin-conserving linear response TD-DFT fails to accurately reproduce the lowest excitation energy in these pi-conjugated systems by strongly overestimating the excitation energies of cyanines and underestimating the excitation energies of n-acenes. The spin-flip TD-DFT is capable of correcting the underestimation of excitation energies of n-acenes by bringing in the non-dynamic electron correlation into the ground state; however, it does not fully correct for the overestimation of the excitation energies of cyanines, for which the non-dynamic correlation does not seem to play a role. The ensemble DFT method employed in this work is capable of correcting for the effect of missing non-dynamic correlation in the ground state of n-acenes and for the deficient description of differential correlation effects between the ground and excited states of cyanines and yields the excitation energies of both types of extended pi-conjugated systems with the accuracy matching high-level ab initio multireference calculations. (C) 2014 AIP Publishing LLC.
Barry Moore - One of the best experts on this subject based on the ideXlab platform.
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Longest-Wavelength Electronic Excitations of Linear Cyanines: The Role of Electron Delocalization and of Approximations in Time-Dependent Density Functional Theory.
Journal of chemical theory and computation, 2013Co-Authors: Barry Moore, Jochen AutschbachAbstract:The lowest-energy/Longest-Wavelength electronic singlet excitation energies of linear cyanine dyes are examined, using time-dependent density functional theory (TDDFT) and selected wave function methods in comparison with literature data. Variations of the bond-length alternation obtained with different optimized structures produce small differences of the excitation energy in the limit of an infinite chain. Hybrid functionals with range-separated exchange are optimally ‘tuned’, which is shown to minimize the delocalization error (DE) in the cyanine π systems. Much unlike the case of charge-transfer excitations, small DEs are not strongly correlated with better performance. A representative cyanine is analyzed in detail. Compared with accurate benchmark data, TDDFT with ‘pure’ local functionals gives too high singlet excitation energies for all systems, but DFT-based ΔSCF calculations with a local functional severely underestimates the energies. TDDFT strongly overestimates the difference between singlet ...
