The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Patrick Georges - One of the best experts on this subject based on the ideXlab platform.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of Thermal Lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:Abstract A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials ( Section 1 ), we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally ( Section 2 ). This is the first step before studying the complex problem of Thermal Lensing ( Section 3 ). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Section 4 will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in Section 5 , we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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Thermal Lensing in diode pumped ytterbium lasers part i theoretical analysis and wavefront measurements
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. In this first part, we focus on theoretical considerations and we describe an original technique suitable for Thermal Lensing measurements in end-pumped materials. We first derive an expression of the temperature distribution with account of absorption saturation and pump beam divergence inside the crystal, and we address a more general discussion on the particularities of quasi-three-level lasers, as far as Thermal effects and fracture issues are concerned. The Thermal lens was then measured using a simple technique based on a Shack-Hartmann wavefront analyzer, under lasing and nonlasing conditions. We demonstrate that the technique allows precise wavefront measurements even on small spots. Thermal Lensing measurements are finally presented in Yb-doped YAG, GGG, YCOB, GdCOB, KGW, and YSO crystals.
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Thermal Lensing in diode pumped ytterbium lasers part ii evaluation of quantum efficiencies and thermo optic coefficients
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. This papers follows the presentation of theoretical considerations and experimental wavefront measurements, which have been the subject of Part I. In this paper, we study the evolution of Thermal Lensing versus absorbed pump power, and we derive two parameters valuable for laser design and power scaling. The quantum efficiency and the thermo-optic coefficient, in Yb-doped YAG, GGG, GdCOB, YCOB, KGW and YSO. The clear difference between Thermal Lensing under lasing and nonlasing conditions is the proof that nonradiative effects occur in all the crystals under investigation. An analytical model which takes into account the laser extraction efficiency enables to explain all the experimental features and allows to infer the fluorescence quantum efficiency of the samples (in the range 0.7-0.96). Under nonlasing conditions, the Thermal lens dioptric power experiences a roll-off, for which we propose an explanation based on the theory presented in Part I. These results are then used to yield the thermo-optic coefficient of the crystals. At last, we propose a simple analytical formulation useful for a rough estimation of the focal length.
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Thermal Lensing measurements in diode pumped yb doped gdcob ycob yso yag and kgw
Optical Materials, 2003Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Patrick Georges, Gaelle Lucasleclin, Yves Fichot, R Gaume, Bruno Viana, Gerard Aka, D VivienAbstract:A Shack–Hartmann wavefront sensor was used to measure Thermal Lensing in diode-end-pumped Yb-doped GdCOB, YCOB, YSO, YAG, and KGW crystals, under lasing or nonlasing conditions. Measured Thermal lenses are aberration-free, and their focal lengths under lasing action range from 40 to 140 mm for 5 W of absorbed power. When laser action was inhibited the Thermal lens dioptric power was increased significantly in most crystals, supplying evidence that nonradiative mechanisms exist. Reduction of Thermal effects in a composite YCOB crystal is also investigated, as well as the dependence of Thermal Lensing on the emission wavelength in YSO. 2002 Elsevier Science B.V. All rights reserved.
Sebastien Chenais - One of the best experts on this subject based on the ideXlab platform.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of Thermal Lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:Abstract A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials ( Section 1 ), we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally ( Section 2 ). This is the first step before studying the complex problem of Thermal Lensing ( Section 3 ). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Section 4 will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in Section 5 , we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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Thermal Lensing in diode pumped ytterbium lasers part i theoretical analysis and wavefront measurements
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. In this first part, we focus on theoretical considerations and we describe an original technique suitable for Thermal Lensing measurements in end-pumped materials. We first derive an expression of the temperature distribution with account of absorption saturation and pump beam divergence inside the crystal, and we address a more general discussion on the particularities of quasi-three-level lasers, as far as Thermal effects and fracture issues are concerned. The Thermal lens was then measured using a simple technique based on a Shack-Hartmann wavefront analyzer, under lasing and nonlasing conditions. We demonstrate that the technique allows precise wavefront measurements even on small spots. Thermal Lensing measurements are finally presented in Yb-doped YAG, GGG, YCOB, GdCOB, KGW, and YSO crystals.
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Thermal Lensing in diode pumped ytterbium lasers part ii evaluation of quantum efficiencies and thermo optic coefficients
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. This papers follows the presentation of theoretical considerations and experimental wavefront measurements, which have been the subject of Part I. In this paper, we study the evolution of Thermal Lensing versus absorbed pump power, and we derive two parameters valuable for laser design and power scaling. The quantum efficiency and the thermo-optic coefficient, in Yb-doped YAG, GGG, GdCOB, YCOB, KGW and YSO. The clear difference between Thermal Lensing under lasing and nonlasing conditions is the proof that nonradiative effects occur in all the crystals under investigation. An analytical model which takes into account the laser extraction efficiency enables to explain all the experimental features and allows to infer the fluorescence quantum efficiency of the samples (in the range 0.7-0.96). Under nonlasing conditions, the Thermal lens dioptric power experiences a roll-off, for which we propose an explanation based on the theory presented in Part I. These results are then used to yield the thermo-optic coefficient of the crystals. At last, we propose a simple analytical formulation useful for a rough estimation of the focal length.
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Thermal Lensing measurements in diode pumped yb doped gdcob ycob yso yag and kgw
Optical Materials, 2003Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Patrick Georges, Gaelle Lucasleclin, Yves Fichot, R Gaume, Bruno Viana, Gerard Aka, D VivienAbstract:A Shack–Hartmann wavefront sensor was used to measure Thermal Lensing in diode-end-pumped Yb-doped GdCOB, YCOB, YSO, YAG, and KGW crystals, under lasing or nonlasing conditions. Measured Thermal lenses are aberration-free, and their focal lengths under lasing action range from 40 to 140 mm for 5 W of absorbed power. When laser action was inhibited the Thermal lens dioptric power was increased significantly in most crystals, supplying evidence that nonradiative mechanisms exist. Reduction of Thermal effects in a composite YCOB crystal is also investigated, as well as the dependence of Thermal Lensing on the emission wavelength in YSO. 2002 Elsevier Science B.V. All rights reserved.
François Balembois - One of the best experts on this subject based on the ideXlab platform.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of Thermal Lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:Abstract A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials ( Section 1 ), we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally ( Section 2 ). This is the first step before studying the complex problem of Thermal Lensing ( Section 3 ). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Section 4 will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in Section 5 , we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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Thermal Lensing in diode pumped ytterbium lasers part i theoretical analysis and wavefront measurements
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. In this first part, we focus on theoretical considerations and we describe an original technique suitable for Thermal Lensing measurements in end-pumped materials. We first derive an expression of the temperature distribution with account of absorption saturation and pump beam divergence inside the crystal, and we address a more general discussion on the particularities of quasi-three-level lasers, as far as Thermal effects and fracture issues are concerned. The Thermal lens was then measured using a simple technique based on a Shack-Hartmann wavefront analyzer, under lasing and nonlasing conditions. We demonstrate that the technique allows precise wavefront measurements even on small spots. Thermal Lensing measurements are finally presented in Yb-doped YAG, GGG, YCOB, GdCOB, KGW, and YSO crystals.
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Thermal Lensing in diode pumped ytterbium lasers part ii evaluation of quantum efficiencies and thermo optic coefficients
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. This papers follows the presentation of theoretical considerations and experimental wavefront measurements, which have been the subject of Part I. In this paper, we study the evolution of Thermal Lensing versus absorbed pump power, and we derive two parameters valuable for laser design and power scaling. The quantum efficiency and the thermo-optic coefficient, in Yb-doped YAG, GGG, GdCOB, YCOB, KGW and YSO. The clear difference between Thermal Lensing under lasing and nonlasing conditions is the proof that nonradiative effects occur in all the crystals under investigation. An analytical model which takes into account the laser extraction efficiency enables to explain all the experimental features and allows to infer the fluorescence quantum efficiency of the samples (in the range 0.7-0.96). Under nonlasing conditions, the Thermal lens dioptric power experiences a roll-off, for which we propose an explanation based on the theory presented in Part I. These results are then used to yield the thermo-optic coefficient of the crystals. At last, we propose a simple analytical formulation useful for a rough estimation of the focal length.
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Thermal Lensing measurements in diode pumped yb doped gdcob ycob yso yag and kgw
Optical Materials, 2003Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Patrick Georges, Gaelle Lucasleclin, Yves Fichot, R Gaume, Bruno Viana, Gerard Aka, D VivienAbstract:A Shack–Hartmann wavefront sensor was used to measure Thermal Lensing in diode-end-pumped Yb-doped GdCOB, YCOB, YSO, YAG, and KGW crystals, under lasing or nonlasing conditions. Measured Thermal lenses are aberration-free, and their focal lengths under lasing action range from 40 to 140 mm for 5 W of absorbed power. When laser action was inhibited the Thermal lens dioptric power was increased significantly in most crystals, supplying evidence that nonradiative mechanisms exist. Reduction of Thermal effects in a composite YCOB crystal is also investigated, as well as the dependence of Thermal Lensing on the emission wavelength in YSO. 2002 Elsevier Science B.V. All rights reserved.
Frédéric Druon - One of the best experts on this subject based on the ideXlab platform.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials, we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally. This is the first step before studying the complex problem of Thermal Lensing (part III). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Part IV will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in part V, we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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On Thermal effects in solid state lasers: the case of ytterbium-doped materials
Progress in Quantum Electronics, 2006Co-Authors: Sebastien Chenais, Sebastien Forget, François Balembois, Frédéric Druon, Patrick GeorgesAbstract:Abstract A review of theoretical and experimental studies of Thermal effects in solid-state lasers is presented, with a special focus on diode-pumped ytterbium-doped materials. A large part of this review provides however general information applicable to any kind of solid-state laser. Our aim here is not to make a list of the techniques that have been used to minimize Thermal effects, but instead to give an overview of the theoretical aspects underneath, and give a state-of-the-art of the tools at the disposal of the laser scientist to measure Thermal effects. After a presentation of some general properties of Yb-doped materials ( Section 1 ), we address the issue of evaluating the temperature map in Yb-doped laser crystals, both theoretically and experimentally ( Section 2 ). This is the first step before studying the complex problem of Thermal Lensing ( Section 3 ). We will focus on some newly discussed aspects, like the definition of the thermo-optic coefficient: we will highlight some misleading interpretations of Thermal Lensing experiments due to the use of the dn/dT parameter in a context where it is not relevant. Section 4 will be devoted to a state-of-the-art of experimental techniques used to measure Thermal Lensing. Eventually, in Section 5 , we will give some concrete examples in Yb-doped materials, where their peculiarities will be pointed out.
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Thermal Lensing in diode pumped ytterbium lasers part i theoretical analysis and wavefront measurements
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. In this first part, we focus on theoretical considerations and we describe an original technique suitable for Thermal Lensing measurements in end-pumped materials. We first derive an expression of the temperature distribution with account of absorption saturation and pump beam divergence inside the crystal, and we address a more general discussion on the particularities of quasi-three-level lasers, as far as Thermal effects and fracture issues are concerned. The Thermal lens was then measured using a simple technique based on a Shack-Hartmann wavefront analyzer, under lasing and nonlasing conditions. We demonstrate that the technique allows precise wavefront measurements even on small spots. Thermal Lensing measurements are finally presented in Yb-doped YAG, GGG, YCOB, GdCOB, KGW, and YSO crystals.
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Thermal Lensing in diode pumped ytterbium lasers part ii evaluation of quantum efficiencies and thermo optic coefficients
IEEE Journal of Quantum Electronics, 2004Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Gaelle Lucasleclin, Patrick GeorgesAbstract:A theoretical and experimental study of Thermal Lensing in Yb-doped crystals is presented. This papers follows the presentation of theoretical considerations and experimental wavefront measurements, which have been the subject of Part I. In this paper, we study the evolution of Thermal Lensing versus absorbed pump power, and we derive two parameters valuable for laser design and power scaling. The quantum efficiency and the thermo-optic coefficient, in Yb-doped YAG, GGG, GdCOB, YCOB, KGW and YSO. The clear difference between Thermal Lensing under lasing and nonlasing conditions is the proof that nonradiative effects occur in all the crystals under investigation. An analytical model which takes into account the laser extraction efficiency enables to explain all the experimental features and allows to infer the fluorescence quantum efficiency of the samples (in the range 0.7-0.96). Under nonlasing conditions, the Thermal lens dioptric power experiences a roll-off, for which we propose an explanation based on the theory presented in Part I. These results are then used to yield the thermo-optic coefficient of the crystals. At last, we propose a simple analytical formulation useful for a rough estimation of the focal length.
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Thermal Lensing measurements in diode pumped yb doped gdcob ycob yso yag and kgw
Optical Materials, 2003Co-Authors: Sebastien Chenais, François Balembois, Frédéric Druon, Patrick Georges, Gaelle Lucasleclin, Yves Fichot, R Gaume, Bruno Viana, Gerard Aka, D VivienAbstract:A Shack–Hartmann wavefront sensor was used to measure Thermal Lensing in diode-end-pumped Yb-doped GdCOB, YCOB, YSO, YAG, and KGW crystals, under lasing or nonlasing conditions. Measured Thermal lenses are aberration-free, and their focal lengths under lasing action range from 40 to 140 mm for 5 W of absorbed power. When laser action was inhibited the Thermal lens dioptric power was increased significantly in most crystals, supplying evidence that nonradiative mechanisms exist. Reduction of Thermal effects in a composite YCOB crystal is also investigated, as well as the dependence of Thermal Lensing on the emission wavelength in YSO. 2002 Elsevier Science B.V. All rights reserved.
Pavel Loiko - One of the best experts on this subject based on the ideXlab platform.
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Thermal Lensing and multiwatt microchip laser operation of yb ycob crystals
IEEE Photonics Journal, 2016Co-Authors: Pavel Loiko, Konstantin Yumashev, Josep Maria Serres, Xavier Mateos, Huaijin Zhang, Junhai Liu, Uwe Griebner, Valentin Petrov, Magdalena Aguilo, Francesc DiazAbstract:Thermal Lensing is studied in monoclinic Yb:Ca 4YO(BO 3) 3 (Yb: YCOB) oxoborate crystals cut along the optical indicatrix axes. For all orientations, the Thermal lens is positive. In the $Z$ -cut crystal, the sensitivity factors of the Thermal lens are $M_{Z-X} = 2.4$ and $M_{Z-Y} = 2.8\ \text{m}^{-1}/\text{W}$ (for $E \| X$ ), and the astigmatism degree is as low as $S/M = 14\%$ . The positive Thermal lens in Yb:YCOB is related to the large Thermal expansion and strong photoelastic effect. Microchip lasers are realized with 3-mm-long $X$ , $Y$ , and $Z$ -cut 15 at.% Yb:YCOB crystals. With a $Z$ -cut crystal, maximum output power of 8.35 W is achieved at ∼1040 nm with slope efficiency of 70%. Using various crystal cuts and output coupler transmissions, multiwatt emission in the spectral range of 1033–1091 nm is demonstrated.
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Thermal Lensing in yb klu wo4 2 crystals cut along the optical indicatrix axes
Laser Physics Letters, 2014Co-Authors: Pavel Loiko, Konstantin Yumashev, N.v. Kuleshov, Josep Maria Serres, Xavier Mateos, Uwe Griebner, Valentin Petrov, Magdalena Aguilo, Francesc DiazAbstract:Thermal Lensing is studied in Yb:KLu(WO4)2 crystals cut along the three optical indicatrix axes, Np, Nm and Ng. The cut along the Ng-axis is the only one that provides a pure positive Thermal lens with the sensitivity factors M = 3.5 and 2.8 m−1 W−1 (wp = 100 μm) for the mg- and pg-planes, respectively, and a low astigmatism degree, S/M < 20%. Both Np-cut and Nm-cut crystals produce different-signed lens with at least six-times stronger astigmatism. This behavior is related to the anisotropy of the photo-elastic effect. A CW Yb:KLu(WO4)2 microchip laser delivering a maximum output power of 992 mW at 1051 nm with a slope efficiency of 40%, and possessing low spatial distortions of the laser beam and M2 < 1.1, is realized on the basis of Ng-cut crystal.
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Thermal Lensing in nm cut monoclinic tm klu wo4 2 laser crystal
Laser Physics Letters, 2013Co-Authors: Pavel Loiko, Konstantin Yumashev, S M Vatnik, I A Vedin, A A Pavlyuk, N.v. KuleshovAbstract:The Thermal Lensing effect is characterized in slab-shaped monoclinic Tm:KLu(WO4)2 crystal cut for light propagation along the Nm optical indicatrix axis (the light polarization is E???Np). The optical power of the Thermal lens was measured directly by a modified probe beam technique. Alternatively, it was calculated on the basis of measured material parameters, including the Thermal expansion coefficients along the optical indicatrix axes (?p?=?3.1, ?m?=?11.1 and ?g?=?13.1(10?6?K?1)) and the principal thermo-optic coefficients (dnp/dT?=??13.3, dnm/dT?=??5.9, dng/dT?=??9.0(10?6?K?1) at 1.95??m). The two methods are in good agreement and confirm the defocusing action of the Thermal lens; the ?effective? thermo-optic coefficient ? for Nm-cut crystal is ?2.1???0.5???10?6?K?1. The fractional head load ?h for slab-shaped Tm:KLu(WO4)2 crystal is 0.33???0.03 (as determined from ISO-standard laser calorimetry).
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Thermal Lensing and microchip laser performance of N g -cut Tm 3+ :KY(WO 4 ) 2 crystal
Applied Physics B, 2012Co-Authors: M. S. Gaponenko, Pavel Loiko, N.v. Gusakova, Konstantin Yumashev, N.v. Kuleshov, Anatoly PavlyukAbstract:The Thermal Lensing effect was characterized in the diode-pumped monoclinic N g-cut Tm:KYW crystal under laser operation conditions at the wavelength of 1.94 μm. The Thermal lens was found to be slightly astigmatic; its optical power D being positive for rays lying in all meridional planes. Thermal lens sensitivity factors M=dD/dP abs equal 11.8 m−1/W and 8.8 m−1/W (with respect to the absorbed pump power P abs) for principal meridional planes containing N p and N m axes. Nearly aThermal behavior of N g-cut crystal is associated with the mutual compensation of different impacts to the Thermal lens optical power that arise from temperature dependence of the refractive index dn/dT and anisotropic Thermal expansion. It was utilized to produce passively cooled diode-pumped 0.65 W cw Tm:KYW microchip laser with slope efficiency of 44 % and low thermo-optic aberrations.
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Thermal Lensing study and aThermal directions in flashlamp pumped nd kgd wo 4 2 laser crystal
Applied Physics B, 2012Co-Authors: Pavel Loiko, Konstantin Yumashev, N.v. Kuleshov, A A PavlyukAbstract:Thermal Lensing has been studied by a probe beam technique in flashlamp-pumped Nd:KGdW laser rods with rod axes positioned in the Np–Ng plane and making different angles with the Ng optical indicatrix axis. It was found that the orientation of principal meridional planes of the astigmatic Thermal lens in Nd:KGdW corresponds to the directions with maximum and minimum values of Thermal-expansion coefficient in the plane perpendicular to the rod axis. The aThermal Nd:KGdW laser crystal orientation defined as orientation with weak positive near spherical Thermal lens has been determined to make an angle of 30○–40○ with the Ng axis for light polarization E∥Nm.
