The Experts below are selected from a list of 21987 Experts worldwide ranked by ideXlab platform
Mark Dubinskii - One of the best experts on this subject based on the ideXlab platform.
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Record-low Quantum Defect operation of an eye-safe Er-doped laser
Laser Physics Letters, 2016Co-Authors: Nikolay Ter-gabrielyan, Viktor Fromzel, Mark DubinskiiAbstract:Several new laser transitions from a resonantly-pumped Er3+:YVO4 laser have been demonstrated. Laser operation with Quantum Defect as low as 0.82% has been achieved. We believe that this is the lowest Quantum Defect operation ever reported for an eye-safe laser.
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resonantly pumped single mode channel waveguide er yag laser with nearly Quantum Defect limited efficiency
Optics Letters, 2013Co-Authors: Nikolay Tergabrielyan, Viktor Fromzel, H Meissner, Mark DubinskiiAbstract:We demonstrated the continuous-wave operation of a resonantly pumped Er:YAG single-mode channel waveguide laser with diffraction-limited output and nearly Quantum Defect limited efficiency. Using a longitudinally core-pumped, nearly square (61.2 μm×61.6 μm) Er3+:YAG waveguide embedded in an undoped YAG cladding, an output power of 9.1 W with a slope efficiency of 92.8% (versus absorbed pump power) has been obtained. To the best of our knowledge, this optical-to-optical efficiency is the highest ever demonstrated for a channel waveguide laser.
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nearly Quantum Defect limited efficiency resonantly pumped er 3 yvo 4 laser at 1593 5 nm
Optics Letters, 2011Co-Authors: Nikolay Tergabrielyan, Viktor Fromzel, T Lukasiewicz, W Rybaromanowski, Mark DubinskiiAbstract:Nearly Quantum-Defect-limited laser operation of a resonantly pumped Er3+:YVO4 at 1593.5 nm is demonstrated. Maximum slope efficiency of ∼85% and true CW power of ∼13 W at 1593.5 nm were achieved with a beam propagation factor of M2∼1.05. This slope efficiency is, to the best of our knowledge, the highest efficiency ever reported for a crystalline Er-doped laser.
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ultralow Quantum Defect eye safe er sc2o3 laser
Optics Letters, 2008Co-Authors: Nikolay Tergabrielyan, Larry D Merkle, Akio Ikesue, Mark DubinskiiAbstract:Resonantly pumped Er3+:Sc2O3 laser operation is achieved with a Quantum Defect (QD) of 1.5% at liquid nitrogen temperature. The laser, in-line pumped at 1535 nm, operated at 1558 nm with a slope efficiency of over 45%. This is believed to be the lowest QD eye-safe laser ever reported. CW output of over 3.3 W was obtained in this first experiment.
Johan Nilsson - One of the best experts on this subject based on the ideXlab platform.
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Ultra-Low Quantum-Defect Heating in Ytterbium-Doped Aluminosilicate Fibers
Journal of Lightwave Technology, 2014Co-Authors: Junhua Ji, Johan NilssonAbstract:We theoretically investigate the Quantum Defect between pump and signal photons in ytterbium-doped fiber lasers and amplifiers, and find that this can be as low as 0.6%. We find that the lowest Quantum Defects can be achieved with a low area ratio between the pump and signal waveguide of a double-clad fiber, and with high-brightness pumping in the core being an ultimate approach. The change in achievable Quantum Defect is small over a relatively large range of pump wavelengths, but it is still necessary to optimize the wavelengths and match the fiber length to reach the smallest Quantum Defect.
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Tandem-pumped ytterbium-doped aluminosilicate fiber amplifier with low Quantum Defect
Conference on Lasers and Electro-Optics 2012, 2012Co-Authors: Tianfu Yao, Jayanta K. Sahu, Andrew S. Webb, Johan NilssonAbstract:We show theoretically that a Quantum-Defect below 1% is possible in tandem-pumped Yb-doped aluminosilicate fibers operating off the gain peak. Experimentally, we reach a Quantum Defect of 2% and a slope efficiency of 90% or more.
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Minimize Quantum-Defect heating in thulium-doped silica fiber amplifiers by tandem-pumping
2012 Photonics Global Conference (PGC), 2012Co-Authors: Seongwoo Yoo, Ping Shum, Johan NilssonAbstract:In this paper, we propose a simple model to investigate the Quantum Defect between pump and signal photons in thulium-doped fiber amplifiers. The achievable Quantum Defects are limited by several factors, i.e., pump and signal wavelengths, fiber length, area ratio between inner cladding and core, and gain and absorption at signal and pump wavelengths, respectively. Through the proposed model, we find that the Quantum Defect can reach as low as 1%-level. We also find that the smaller area ratio between inner cladding and core, the lower Quantum Defect can be obtained. The ultimate pumping approach will be core pumping. This can be realized through tandem pumping the thulium-doped fiber by the other fiber source at shorter wavelength with high brightness. Finally, it is necessary to optimize the pump and signal wavelengths and match the fiber length to obtain the lowest Quantum Defect.
Ch. Jungen - One of the best experts on this subject based on the ideXlab platform.
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elements of Quantum Defect theory
Handbook of High-resolution Spectroscopy, 2011Co-Authors: Ch. JungenAbstract:Quantum Defect theory (QDT) is concerned with the interaction of a single particle with an (atomic or molecular) target, which may be in an ionized or a neutral state. The formalism provides a unified theory of bound state spectroscopy, resonance phenomena, as well as elastic and inelastic scattering processes. In its most common formulation, Quantum Defect theory refers to Coulomb systems, particularly an electron moving in the field of a positively charged ion, and hence it is a theoretical tool for the description of atomic or molecular Rydberg states. The present article emphasizes the foundations of the theory, but a number of applications are also considered. Keywords: spectroscopy; electronically excited states; Rydberg states; channel interactions; elastic and inelastic collisions; spectral perturbations; autoionization; predissociation
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Handbook of High‐resolution Spectroscopy - Elements of Quantum Defect Theory
Handbook of High-resolution Spectroscopy, 2011Co-Authors: Ch. JungenAbstract:Quantum Defect theory (QDT) is concerned with the interaction of a single particle with an (atomic or molecular) target, which may be in an ionized or a neutral state. The formalism provides a unified theory of bound state spectroscopy, resonance phenomena, as well as elastic and inelastic scattering processes. In its most common formulation, Quantum Defect theory refers to Coulomb systems, particularly an electron moving in the field of a positively charged ion, and hence it is a theoretical tool for the description of atomic or molecular Rydberg states. The present article emphasizes the foundations of the theory, but a number of applications are also considered. Keywords: spectroscopy; electronically excited states; Rydberg states; channel interactions; elastic and inelastic collisions; spectral perturbations; autoionization; predissociation
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Quantum Defect theory of dipole-mixed Rydberg states in CaF
Canadian Journal of Physics, 2001Co-Authors: Ch. Jungen, A. L. RocheAbstract:491 rovibronic levels of electronically highly excited CaF have been analyzed using multichannel Quantum Defect theory (MQDT). These levels, observed in the experiments described in the preceding paper, correspond to effective principal Quantum numbers ν 1218, partial wave components l = 03, and vibrationrotation Quantum numbers ν = 1 and N = 014. A set of nondiagonal Quantum Defect matrices has been extracted from the experimental data by means of a global least-squares-fitting procedure, and is found to agree reasonably well with the theoretical Quantum Defect matrices calculated previously by Arif et al. J. Chem. Phys. 106, 4102 (1997) where the variational R-matrix method was used. The MQDT analysis accounts for rotationalelectronic nonadiabatic decoupling of the Rydberg electron from the rotating dipolar core as well as for strong l-mixing induced by the latter. The Quantum Defects determined for l = 3 yield approximate values for the core dipole and quadrupole moments. PACS Nos.: 33.10Lb, 34.50...
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On the construction of basis functions for Quantum Defect theory in arbitrary fields
Journal of Physics B: Atomic Molecular and Optical Physics, 2000Co-Authors: Ch. Jungen, F. TexierAbstract:A numerical method is described for the evaluation of the regular and irregular basis functions used in Quantum Defect theory for arbitrary potentials (generalized Quantum Defect theory). The method is related to Milne's phase-amplitude method and yields phase and amplitude parameters which vary smoothly with energy and radius. It also permits the evaluation of these parameters for strongly closed channels, in the absence of a classically accessible radial range.
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Fine structure of the 4f complexes of ArH and KrH revisited: Quantum Defect theory used as a spectroscopic tool
The Journal of Chemical Physics, 1999Co-Authors: Ch. Jungen, A. L. RocheAbstract:The 4f,v=0 manifolds of levels of ArH, ArD, and KrD observed by Dabrowski et al. [J. Mol. Spectrosc. 189, 110 (1998)] and Dabrowski and Sadovskii [J. Chem. Phys. 107, 8874 (1997)] have been reanalyzed using multichannel Quantum Defect theory. The nondiagonal (l-mixing) Quantum Defect matrices are partially extracted from the experimental data and are found to be in reasonable agreement with the Quantum Defects calculated theoretically by Jungen et al. [Phil. Trans. R. Soc. Lond. A 355, 1481 (1997)]. The Quantum Defect calculations reproduce the observed level fine structure in great detail including nonadiabatic rotational l-uncoupling and electronic l-mixing perturbations.
Nikolay Tergabrielyan - One of the best experts on this subject based on the ideXlab platform.
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resonantly pumped single mode channel waveguide er yag laser with nearly Quantum Defect limited efficiency
Optics Letters, 2013Co-Authors: Nikolay Tergabrielyan, Viktor Fromzel, H Meissner, Mark DubinskiiAbstract:We demonstrated the continuous-wave operation of a resonantly pumped Er:YAG single-mode channel waveguide laser with diffraction-limited output and nearly Quantum Defect limited efficiency. Using a longitudinally core-pumped, nearly square (61.2 μm×61.6 μm) Er3+:YAG waveguide embedded in an undoped YAG cladding, an output power of 9.1 W with a slope efficiency of 92.8% (versus absorbed pump power) has been obtained. To the best of our knowledge, this optical-to-optical efficiency is the highest ever demonstrated for a channel waveguide laser.
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nearly Quantum Defect limited efficiency resonantly pumped er 3 yvo 4 laser at 1593 5 nm
Optics Letters, 2011Co-Authors: Nikolay Tergabrielyan, Viktor Fromzel, T Lukasiewicz, W Rybaromanowski, Mark DubinskiiAbstract:Nearly Quantum-Defect-limited laser operation of a resonantly pumped Er3+:YVO4 at 1593.5 nm is demonstrated. Maximum slope efficiency of ∼85% and true CW power of ∼13 W at 1593.5 nm were achieved with a beam propagation factor of M2∼1.05. This slope efficiency is, to the best of our knowledge, the highest efficiency ever reported for a crystalline Er-doped laser.
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ultralow Quantum Defect eye safe er sc2o3 laser
Optics Letters, 2008Co-Authors: Nikolay Tergabrielyan, Larry D Merkle, Akio Ikesue, Mark DubinskiiAbstract:Resonantly pumped Er3+:Sc2O3 laser operation is achieved with a Quantum Defect (QD) of 1.5% at liquid nitrogen temperature. The laser, in-line pumped at 1535 nm, operated at 1558 nm with a slope efficiency of over 45%. This is believed to be the lowest QD eye-safe laser ever reported. CW output of over 3.3 W was obtained in this first experiment.
Cornel Hategan - One of the best experts on this subject based on the ideXlab platform.
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Siegert state approach to Quantum Defect theory
The European Physical Journal D, 2020Co-Authors: Cornel Hategan, Remus-amilcar Ionescu, H. H. WolterAbstract:The Siegert states are approached in framework of Bloch-Lane-Robson formalism for Quantum collisions. The Siegert state is not described by a pole of Wigner R-matrix but rather by the equation 1 − R nn L n = 0, relating R-matrix element R nn to decay channel logarithmic derivative L n . Extension of Siegert state equation to multichannel system results in the replacement of channel R- matrix element R nn by its reduced counterpart R nn . One proves the Siegert state is a pole, (1 − R nn L n )−1 , of multichannel collision matrix. The Siegert equation 1 − R nn L n = 0, (n – Rydberg channel), implies basic results of Quantum Defect Theory as Seaton’s theorem, complex Quantum Defect, channel resonances and threshold continuity of averaged multichannel collision matrix elements.
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Siegert State Approach to Quantum Defect Theory
arXiv: Atomic Physics, 2016Co-Authors: Cornel Hategan, Remus-amilcar Ionescu, H. H. WolterAbstract:The Siegert states are approached in framework of Bloch-Lane-Robson formalism for Quantum collisions. The Siegert state is not described by a pole of Wigner R- matrix but rather by the equation $1- R_{nn}L_n = 0$, relating R- matrix element $R_{nn}$ to decay channel logarithmic derivative $L_n$. Extension of Siegert state equation to multichannel system results into replacement of channel R- matrix element $R_{nn}$ by its reduced counterpart ${\cal R}_{nn}$. One proves the Siegert state is a pole, $(1 - {\cal R}_{nn} L_{n})^{-1}$, of multichannel collision matrix. The Siegert equation $1 - {\cal R}_{nn} L_{n} = 0$, ($n$ - Rydberg channel), implies basic results of Quantum Defect Theory as Seaton's theorem, complex Quantum Defect, channel resonances and threshold continuity of averaged multichannel collision matrix elements.
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MULTICHANNEL Quantum Defect AND REDUCED R-MATRIX
2007Co-Authors: Cornel Hategan, Remus-amilcar IonescuAbstract:This work demonstrates that the Multichannel Quantum Defect Theory and the Reduced R-Matrix are formally related and physically equivalent; both theories describe not only the internal dynamics but also the interactions in space of eliminated channels. The Multichannel Quantum Defect Theory is, according to present approach, a general framework relating collision matrices of two reaction systems which differ only in dynamics of eliminated channels.
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Level-matrix approach to multichannel Quantum Defect theory
Journal of Physics B: Atomic Molecular and Optical Physics, 1995Co-Authors: Cornel Hategan, Remus-amilcar IonescuAbstract:The multichannel Quantum Defect theory is derived by using the level-matrix parametrization of the collision matrix. It is proved that the specific aspects of the multichannel Quantum Defect theory originate in the jump across threshold of the logarithmic derivative. The connections to the reduced collision matrix and to the threshold cusp theory are established.
