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28 results on '"Eismann, Ulrich"'

1. Fabry-P\'{e}rot etalon walk-off loss in ring cavities

Author

Eismann, Ulrich

Subjects
Quantum Physics, Physics - Atomic Physics, Physics - Optics
Abstract

Fabry-P\'erot etalons are widely used for laser frequency control. Inserting them in laser cavities imparts unavoidable walk-off loss and reduces the output power. Here, we treat the technology-relevant case of the walk-off loss of an etalon in a unidirectional ring cavity, which is a standard design of single-frequency lasers. We provide the theory background by discussing the analytic limits. The loss can be efficiently minimized by realignment, or by proper matching of the etalon's surface reflectivity with its refractive index. We numerically calculate the loss in the region uncovered by the analytic limits. We discuss practical laser design considerations, and we perform a tilt-tuning experiment in a single-frequency, solid-state laser setup.

Published
2025

2. Active and passive stabilization of a high-power UV frequency-doubled diode laser

Author

Eismann, Ulrich, Enderlein, Martin, Simeonidis, Konstantinos, Keller, Felix, Rohde, Felix, Opalevs, Dmitrijs, Scholz, Matthias, Kaenders, Wilhelm, and Stuhler, Jürgen

Subjects
Physics - Atomic Physics, Condensed Matter - Quantum Gases, Physics - Optics
Abstract

We present a resonantly frequency-doubled tapered amplified semiconductor laser system emitting up to 2.6 W blue light at 400 nm. The output power is stable on both short and long timescales with 0.12% RMS relative intensity noise, and less than 0.15%/h relative power loss over 16 hours of free running continuous operation. Furthermore, the output power can be actively stabilized, and the alignment of the input beams of the tapered amplifier chip, the frequency doubling cavity and-in case of fiber output-the fiber can be optimized automatically using computer-controlled mirrors.

Published
2016
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3. Comment on: Investigation of the thermal lens effect of the TGG crystal in high-power frequency-doubled laser with single frequency operation

Author

Eismann, Ulrich

Subjects
Physics - Optics
Abstract

In their article, the authors of [Opt. Express 23, 4981 (2015)] observe step-like behavior and hysteresis of the output power of a diode-end-pumped Nd:YVO 4-laser as a function of pump power. While claiming that this behavior is a proof of thermal lensing in the intra-cavity TGG, no direct evidence is given. We will discuss here the validity of their statement, and propose an experimental proof.

Published
2015

4. Universal Loss Dynamics in a Unitary Bose Gas

Author

Eismann, Ulrich, Khaykovich, Lev, Laurent, Sébastien, Ferrier-Barbut, Igor, Rem, Benno S., Grier, Andrew T., Delehaye, Marion, Chevy, Frédéric, Salomon, Christophe, Ha, Li-Chung, and Chin, Cheng

Subjects
Condensed Matter - Quantum Gases, Physics - Atomic Physics
Abstract

The low temperature unitary Bose gas is a fundamental paradigm in few-body and many-body physics, attracting wide theoretical and experimental interest. Here we first present a theoretical model that describes the dynamic competition between two-body evaporation and three-body re-combination in a harmonically trapped unitary atomic gas above the condensation temperature. We identify a universal magic trap depth where, within some parameter range, evaporative cooling is balanced by recombination heating and the gas temperature stays constant. Our model is developed for the usual three-dimensional evaporation regime as well as the 2D evaporation case. Experiments performed with unitary 133 Cs and 7 Li atoms fully support our predictions and enable quantitative measurements of the 3-body recombination rate in the low temperature domain. In particular, we measure for the first time the Efimov inelasticity parameter $\eta$ * = 0.098(7) for the 47.8-G d-wave Feshbach resonance in 133 Cs. Combined 133 Cs and 7 Li experimental data allow investigations of loss dynamics over two orders of magnitude in temperature and four orders of magnitude in three-body loss. We confirm the 1/T 2 temperature universality law up to the constant $\eta$ *.

Published
2015
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5. 2.1-watts intracavity-frequency-doubled all-solid-state light source at 671 nm for laser cooling of lithium

Author

Eismann, Ulrich, Andrea, Bergschneider, Salomon, Christophe, and Chevy, Frédéric

Subjects
Physics - Optics, Condensed Matter - Quantum Gases, Physics - Atomic Physics
Abstract

We present an all-solid-state laser source emitting up to 2.1 W of single-frequency light at 671 nm developed for laser cooling of lithium atoms. It is based on a diode-pumped, neodymium-doped orthovanadate (Nd:YVO$_4$) ring laser operating at 1342 nm. Optimization of the thermal management in the gain medium results in a maximum multi-frequency output power of 2.5 W at the fundamental wavelength. We develop a simple theory for the efficient implementation of intracavity second harmonic generation, and its application to our system allows us to obtain nonlinear conversion efficiencies of up to 88%. Single-mode operation and tuning is established by adding an etalon to the resonator. The second-harmonic wavelength can be tuned over 0.5 nm, and mode-hop-free scanning over more than 6 GHz is demonstrated, corresponding to around ten times the laser cavity free spectral range. The output frequency can be locked with respect to the lithium $D$-line transitions for atomic physics applications. Furthermore, we observe parametric Kerr-lens mode-locking when detuning the phase-matching temperature sufficiently far from the optimum value.

Published
2013
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6. Strongly Interacting Two-Dimensional Bose Gases

Author

Ha, Li-Chung, Hung, Chen-Lung, Zhang, Xibo, Eismann, Ulrich, Tung, Shih-Kuang, and Chin, Cheng

Subjects
Condensed Matter - Quantum Gases
Abstract

We prepare and study strongly interacting two-dimensional Bose gases in the superfluid, the classical Berezinskii-Kosterlitz-Thouless (BKT) transition, and the vacuum-to-superfluid quantum critical regimes. A wide range of the two-body interaction strength 0.05 < g < 3 is covered by tuning the scattering length and by loading the sample into an optical lattice. Based on the equations of state measurements, we extract the coupling constants as well as critical thermodynamic quantities in different regimes. In the superfluid and the BKT transition regimes, the extracted coupling constants show significant down-shifts from the mean-field and perturbation calculations when g approaches or exceeds one. In the BKT and the quantum critical regimes, all measured thermodynamic quantities show logarithmic dependence on the interaction strength, a tendency confirmed by the extended classical-field and renormalization calculations., Comment: 5 pages, 4 figures

Published
2012
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7. An all-solid-state laser source at 671 nm for cold atom experiments with lithium

Author

Eismann, Ulrich, Gerbier, Fabrice, Canalias, Carlota, Zukauskas, Andrius, Trénec, Gérard, Vigué, Jacques, Chevy, Frédéric, and Salomon, Christophe

Subjects
Physics - Optics, Condensed Matter - Quantum Gases, Physics - Atomic Physics
Abstract

We present an all solid-state narrow line-width laser source emitting $670\,\mathrm{mW}$ output power at $671\,\mathrm{nm}$ delivered in a diffraction-limited beam. The \linebreak source is based on a fre-quency-doubled diode-end-linebreak pumped ring laser operating on the ${^4F}_{3/2} \rightarrow {^4I}_{13/2}$ transition in Nd:YVO$_4$. By using periodically-poled po-tassium titanyl phosphate (ppKTP) in an external build-up cavity, doubling efficiencies of up to 86% are obtained. Tunability of the source over $100\,\rm GHz$ is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally a simplified design based on intra-cavity doubling is described and first results are presented.

Published
2011
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8. Large atom number dual-species magneto-optical trap for fermionic 6Li and 40K atoms

Author

Ridinger, Armin, Chaudhuri, Saptarishi, Salez, Thomas, Eismann, Ulrich, Fernandes, Diogo Rio, Wilkowski, David, Chevy, Frédéric, and Salomon, Christophe

Subjects
Condensed Matter - Quantum Gases
Abstract

We present the design, implementation and characterization of a dual-species magneto-optical trap (MOT) for fermionic 6Li and 40K atoms with large atom numbers. The MOT simultaneously contains 5.2x10^9 6Li-atoms and 8.0x10^9 40K-atoms, which are continuously loaded by a Zeeman slower for 6Li and a 2D-MOT for 40K. The atom sources induce capture rates of 1.2x10^9 6Li-atoms/s and 1.4x10^9 40K-atoms/s. Trap losses due to light-induced interspecies collisions of ~65% were observed and could be minimized to ~10% by using low magnetic field gradients and low light powers in the repumping light of both atomic species. The described system represents the starting point for the production of a large-atom number quantum degenerate Fermi-Fermi mixture.

Published
2011
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12. Laser Rack Systems for Quantum Technologies

Author

Rohde, Felix, primary, Neuhaus, Rudolf, additional, Ritter, Stephan, additional, Falke, Stephan, additional, Eismann, Ulrich, additional, Kienle, Florian, additional, Brakhane, Stefan, additional, Heizenreder, Benedikt, additional, Horvath-Klein, Ruben, additional, and Stuhler, Jürgen, additional

Published
2020
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17. A novel all-solid-state laser source for lithium atoms and three-body recombination in the unitary Bose gas

Author

Eismann, Ulrich, Eismann, Ulrich, Laboratoire Kastler Brossel (LKB (Lhomond)), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris VI, M. Frédéric Chevy, Ferlodim, Université Pierre et Marie Curie - Paris 6 (UPMC)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Doublage de fréquence, [PHYS.PHYS.PHYS-OPTICS] Physics [physics]/Physics [physics]/Optics [physics.optics], [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Pertes à trois corps, Laser cooling of atoms, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], [PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], Diode-pumped solid state lasers, Three-body loss, Thermodynamique, Refroidissement d'atomes par laser, Lasers à état solide pompés par diode, Frequency doubling, Gaz de Bose unitaire, Unitary Bose gas, Thermodynamics, [PHYS.COND.GAS] Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], [PHYS.PHYS.PHYS-ATOM-PH] Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph]
Abstract

In this thesis we present novel techniques for the study of ultracold gases of lithium atoms. In the first part of this thesis, we present the development of a narrow-linewidth laser source emitting 840mW of output power in the vicinity of the lithium D-line resonances at 671 nm. The source is based on a diode-end-pumped unidirectional ring laser operating on the 1342-nm transition in Nd:YVO4, capable of producing 1.3W of single-mode light delivered in a diffraction-limited beam. The output beam is subsequently frequency-doubled using periodically-poled potassium titanyl phosphate (ppKTP) in an external buildup cavity. We obtain doubling efficiencies of up to 86%. Tunability of the output frequency over more than 400GHz and frequency-locking of the cavity ensemble with respect to the lithium D-line transitions are accomplished. We measure the linewidth to be 200+400-200kHz. In the second part of this thesis, we employ the source in an experimental setup to produce to cool and trap lithium atoms. We realize samples of finite-temperature unitary Bose gases around the center of a Fano-Feshbach resonance, where interactions between the atoms are maximized. We present temperature-dependent measurements of the unitarity-limited three-body loss rate. The measured losses attain the limiting value imposed by quantum mechanics without adjustable parameters. This measurement allows for the introduction of a criterion for quasi-equilibrium. In this regime, by using technique based on in-situ imaging developed in our group, we provide a first measurement of the equation of state of the unitary Bose gas at low fugacities., Dans cette thèse, nous présentons des nouvelles techniques et leur application dans l'étude des gaz d'atomes de lithium ultrafroids. Dans la première partie de cette thèse, nous présentons le développement d'une nouvelle source laser de faible largeur spectrale, capable d'émettre 840mW de puissance dans la gamme des longeurs d'ondes des raies D du lithium atomique à 671nm. La source est basée sur un laser en anneau pompé par diode, capable de produire 1.3W de lumière à 1342nm monomode. Le faisceau de sortie est ensuite doublé en fréquence dans un cristal de phosphate de potassium titanyl (ppKTP) périodiquement polarisé dans une cavité externe. Nous obtenons un rendement du doublage de 86%. Une accordabilité de la fréquence de sortie sur plus de 400GHz et le verrouillage de l'ensemble des cavités par rapport aux raies du lithium sont accomplis. Nous avons mesuré la largeur de raie d'émission à 200+-400kHz. Dans la deuxième partie de cette thèse, nous employons la source sur un dispositif expérimental pour refroidir et piéger des atomes de lithium. Nous réalisons des echantillons du gaz de Bose unitaire à température finie au voisinage d'une résonance de Fano-Feshbach. Nous présentons des mesures du taux de pertes à trois corps en fonction de la température. Les pertes mésurées atteignent la valeur limite imposée par la mécanique quantique sans aucun paramètre ajustable. Cette mesure permet l'introduction d'un critère de quasi-équilibre. Dans ce régime, en utilisant une technique basée sur l'imagerie in-situ développée dans notre groupe, nous fournissons une première mesure de l'équation d'état du gaz de Bose unitaire à basse fugacité.

Published
2012

18. Cavity-enhanced non-destructive detection of atomic populationsin optical lattice clocks

Author

Le Targat, Rodolphe, Shi, Chunyan, Eismann, Ulrich, Robyr, Jean-Luc, Lodewyck, Jérôme, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Métrologie des fréquences optiques, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2014

19. Universal Loss Dynamics in a Unitary Bose Gas

Author

Eismann, Ulrich, primary, Khaykovich, Lev, additional, Laurent, Sébastien, additional, Ferrier-Barbut, Igor, additional, Rem, Benno S., additional, Grier, Andrew T., additional, Delehaye, Marion, additional, Chevy, Frédéric, additional, Salomon, Christophe, additional, Ha, Li-Chung, additional, and Chin, Cheng, additional

Published
2016
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20. Cavity-enhanced non-destructive detection of atomic populations inoptical lattice clocks

Author

Le Targat, Rodolphe, Shi, Chunyan, Eismann, Ulrich, Robyr, Jean-Luc, Lodewyck, Jérôme, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Métrologie des fréquences optiques, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2014

21. Realization of an optical second with lattice clocks

Author

Le Targat, Rodolphe, Shi, Chunyan, Eismann, Ulrich, Robyr, Jean-Luc, Gurov, Mikhail, Le Coq, Yann, Guéna, Jocelyne, Abgrall, Michel, Rosenbusch, Peter, Rovera, Daniele, Bize, Sébastien, Laurent, Philippe, Lodewyck, Jérôme, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Métrologie des fréquences optiques, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Références micro-ondes et échelles de temps

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2013

22. Optical lattice clocks: are we ready for a new definition of the second ?

Author

Shi, Chunyan, Eismann, Ulrich, Robyr, Jean-Luc, Le Targat, Rodolphe, Lodewyck, Jérôme, Systèmes de Référence Temps Espace (SYRTE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Métrologie des fréquences optiques, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
Abstract

International audience

Published
2013

25. Direct and frequency-converted diode lasers provide all wavelengths for holography.

Author

EISMANN, ULRICH and PAASCH-COLBERG, TIM

Subjects
*HOLOGRAPHY, *SEMICONDUCTOR lasers, *SEMICONDUCTOR laser manufacturing, *HOLOGRAPHIC optical elements, *WAVELENGTHS
Abstract

The article looks at the impact of new generation of direct and frequency-converted diode lasers on applications of holography. Topics include advances in microintegration of optical components, principles of optical holography, and the advantage of diode lasers and coverage of standard laser diodes. Examples of consumer applications of holography which range from security holograms on credit cards to medical imaging and augmented reality are offered.

Published
2018

27. Short, shorter, shortest: Diode lasers in the deep ultraviolet.

Author

EISMANN, ULRICH, SCHOLZ, MATTHIAS, PAASCH-COLBERG, TIM, and STUHLER, JÜRGEN

Subjects
*SEMICONDUCTOR lasers, *OPTOELECTRONIC devices, *ULTRAVIOLET lasers, *IMAGING systems, *OPTICAL devices
Abstract

The article discusses the use of frequency-converted diode lasers to support continuous-wave light down in the vacuum ultraviolet (UV). Information about the photonics applications in research and industry and other types of conventional laser systems, is provided. Also highlighted are the laser sources operating in the deep-ultraviolet (DUV) range for streamline industrial and scientific applications.

Published
2016

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