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Jianda Shao - One of the best experts on this subject based on the ideXlab platform.
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comparison of 355 nm nanosecond and 1064 nm picosecond laser Induced Damage in high reflective coatings
Optical Engineering, 2018Co-Authors: Yuanan Zhao, Yun Cui, Xiaocong Peng, Chong Shan, Meiping Zhu, Jianguo Wang, Jianda ShaoAbstract:The Damage properties of multilayer coatings tested with 1064-nm 30-ps pulses are similar to those tested with 355 nm, nanosecond pulses. A kind of HfO2 / SiO2 high-reflective (HR) coating is prepared by electron beam evaporation. Laser-Induced Damage of HfO2 / SiO2 HR coatings is tested by 355-nm 7-ns pulses and 1064-nm 30-ps pulses, respectively. Damage morphologies and cross-sectional profiles are characterized using a scanning electron microscope and focused ion beam, respectively. The laser-Induced Damage thresholds and morphologies in the two tests are compared. The developing processes and Damage mechanisms are discussed. Many similarities are found in the two tests: the typical Damage morphologies in both tests appeared as micrometer-sized pits when irradiated by low-fluence pulses, while it turned out to be layer delamination when irradiated by high-fluence pulses. Damage onset is nearby the peak of the E-field in the two tests. Damage pits in both tests may be related to thermal stress caused by nanometer-sized isolated absorbers. There are also some differences in the Damage properties between two tests: Damage pits in 1064-nm 30-ps tests have a much higher density than that in 355-nm 7-ns tests. The detail features and the developing processes of the pits are different.
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comparison of 355 nm nanosecond and 1064 nm picosecond laser Induced Damage in high reflective coatings
Pacific-Rim Laser Damage 2018: Optical Materials for High-Power Lasers, 2018Co-Authors: Yuanan Zhao, Yun Cui, Xiaocong Peng, Chong Shan, Meiping Zhu, Jianguo Wang, Jianda ShaoAbstract:Laser-Induced Damage in optical components has always been a key challenge in the development of high-power laser systems. In picosecond regime, the laser-matter interactions are quite complex and the Damage mechanism is not yet understood. Therefore, it is necessary to investigate the laser Induced Damage of optical components in picosecond regime. Our previous study on the laser Induced Damage in HfO2/SiO2 high-reflective (HR) coatings in 30-ps laser pulses reported the Damage morphologies to be high-density micrometer-scale pits, which are similar to the morphologies of HR coatings irradiated by 355-nm pulses in nanosecond regime. Thus, it makes sense to analyze the Damage mechanism of HR coatings in picosecond regime by comparing the Damage results with those tested with 355-nm pulses. In this study, laser Induced Damage of HfO2/SiO2 HR coatings are performed by 355-nm, 7-ns pulses and 1064-nm, 30-ps pulses, respectively. Different angles of incidence (AOIs) are operated in the tests, in order to modulate the electric field (E-intensity) distributions in the coating stacks. Damage morphologies and cross-sectional profiles are characterized using scanning electron microscope (SEM) and focused ion beam (FIB), respectively. The laser-Induced Damage thresholds (LIDTs) and morphologies tested with two different laser pulses are compared. The Damage locations are compared with corresponding E-field distributions and the Damage reasons are discussed.
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femtosecond laser Induced Damage initiation mechanism on metal multilayer dielectric gratings for pulse compression
Optical Materials, 2018Co-Authors: Haopeng Huang, Fanyu Kong, Zhilin Xia, Yunxia Jin, Leilei Wang, Junming Chen, Yun Cui, Jianda ShaoAbstract:Abstract The femtosecond-laser-Induced Damage behaviors of metal multilayer dielectric gratings (MMDG) for pulse compression are explored. The grating ridge of this type of MMDG consists of a layer of HfO2 sandwiched between two SiO2 layers. The initial Damage position is on the HfO2 layer of the ridge which opposite to the laser beam direction. A theoretical model is constructed to explain the femtosecond-laser-Induced Damage initiation mechanism on the MMDG, and the model can simulate the evolution of the electron density in the conduction band and the change of the dielectric constants of HfO2 and SiO2 in the sandwiched grating structure. The dramatic increase in the imaginary part of the dielectric constant of the middle HfO2 layer indicates that it strongly absorbs laser energy, resulting in Damage to the MMDG. The experimental results and theoretical calculation agree very well with each other.
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effects of annealing on laser Induced Damage threshold of tio2 sio2 high reflectors
Applied Surface Science, 2007Co-Authors: Jianke Yao, Jianda Shao, Zhengxiu FanAbstract:Abstract The mechanism of improving 1064 nm, 12 ns laser-Induced Damage threshold (LIDT) of TiO 2 /SiO 2 high reflectors (HR) prepared by electronic beam evaporation from 5.1 to 13.1 J/cm 2 by thermal annealing is discussed. Through optical properties, structure and chemical composition analysis, it is found that the reduced atomic non-stoichiometric defects are the main reason of absorption decrease and LIDT rise after annealing. A remarkable increase of LIDT is found at 300 °C annealing. The refractive index and film inhomogeneity rise, physical thickness decrease, and film stress changes from compress stress to tensile stress due to the structure change during annealing.
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high laser Induced Damage threshold hfo2 films prepared by ion assisted electron beam evaporation
Applied Surface Science, 2005Co-Authors: Shuhai Fan, Jianda Shao, Yuanan Zhao, Weidong Gao, Ruiying Fan, Yingjian Wang, Zhengxiu FanAbstract:HfO2 films were deposited by electron beam evaporation with different deposition parameters. The properties such as refractive index, weak absorption, and laser Induced Damage thresholds (LIDTs) of these films have been investigated. It was found that when pulsed Nd:YAG 1064 nm laser is used to investigate LIDT of films: Metallic character is the main factor that influences LIDTs of films obtained from Hf starting material by ion-assisted reaction, and films prepared with higher momentum transfer parameter P have fewer metallic character; The ion-assisted reaction parameters are key points for preparing high LIDT films and if the parameters are chose properly, high LIDT films can be obtained. (c) 2004 Elsevier B.V. All rights reserved.
Mireille Commandre - One of the best experts on this subject based on the ideXlab platform.
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wavelength dependence of femtosecond laser Induced Damage threshold of optical materials
Journal of Applied Physics, 2015Co-Authors: Laurent Gallais, Mireille Commandre, D B Douti, Gintarė Bataviciūtė, Egidijus Pupka, Mindaugas Sciuka, Linas Smalakys, Valdas Sirutkaitis, Andrius MelninkaitisAbstract:An experimental and numerical study of the laser-Induced Damage of the surface of optical material in the femtosecond regime is presented. The objective of this work is to investigate the different processes involved as a function of the ratio of photon to bandgap energies and compare the results to models based on nonlinear ionization processes. Experimentally, the laser-Induced Damage threshold of optical materials has been studied in a range of wavelengths from 1030 nm (1.2 eV) to 310 nm (4 eV) with pulse durations of 100 fs with the use of an optical parametric amplifier system. Semi-conductors and dielectrics materials, in bulk or thin film forms, in a range of bandgap from 1 to 10 eV have been tested in order to investigate the scaling of the femtosecond laser Damage threshold with the bandgap and photon energy. A model based on the Keldysh photo-ionization theory and the description of impact ionization by a multiple-rate-equation system is used to explain the dependence of laser-breakdown with the...
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bulk laser Induced Damage threshold of titanium doped sapphire crystals
Applied Optics, 2012Co-Authors: Benoit Bussiere, Jeanyves Natoli, Mireille Commandre, O Uteza, M Sentis, N Sanner, G Riboulet, L Vigroux, Frank R Wagner, J P ChambaretAbstract:The bulk laser-Induced Damage threshold (LIDT) fluence of Ti:sapphire is determined under single-pulse irradiation from the femtosecond to nanosecond temporal regimes in the visible and near-infrared spectral domains. In the range of explored laser conditions, the LIDT fluence increases with both pulse duration and wavelength. The results are also compared to laser interaction with sapphire samples and show an increased resistance to laser Damage when the material is doped with Ti3+ ions. These conclusions are of interest for robust operation of high-peak-power femtosecond Ti:sapphire laser chains.
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model for nanosecond laser Induced Damage in potassium titanyl phosphate crystals
Applied Physics Letters, 2011Co-Authors: Frank Wagner, Anne Hildenbrand, Jeanyves Natoli, Grégoire Duchâteau, Mireille CommandreAbstract:A model for nanosecond laser Induced Damage in the bulk of potassium titanyl phosphate nonlinear optical crystals is presented. In a first step, laser-Induced Damage precursors are produced by multiphoton absorption. In a second step, the Damage precursors are activated. Damage occurs if the precursor activation rate exceeds a critical value. Basic considerations allow evaluating the parameters of the model. The validity of the model is discussed by comparing it to several experimental observations, in particular, the decrease of the laser Damage threshold during second harmonic generation of 1064 nm pulses.
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laser Induced Damage of sapphire and titanium doped sapphire crystals under femtosecond to nanosecond laser irradiation
Laser Damage Symposium XLI: Annual Symposium on Optical Materials for High Power Lasers, 2009Co-Authors: Benoit Bussiere, Jeanyves Natoli, Mireille Commandre, O Uteza, N Sanner, Marc L Sentis, G Riboulet, L Vigroux, Frank R Wagner, J P ChambaretAbstract:The use of large Ti:Sapphire crystals in ultra fast high peak power laser amplifiers makes crucial the problem of crystal laser Induced Damage. These works aim to quantify the laser Induced Damage threshold (LIDT) of Sapphire and Ti:Sapphire crystals under femtosecond, picosecond and nanosecond laser pulse irradiations, which are typically encountered in such laser chains. Furthermore, a study of the influence of cryogenic conditions on the LIDT of Ti:Sapphire crystals and of their anti-reflection coating has been performed. The results are important to understand the mechanisms leading to the Damage, and to reveal the key parameters which will have to be optimized in future high peak power laser chains.
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multiscale analysis of the laser Induced Damage threshold in optical coatings
Applied Optics, 2008Co-Authors: Jeremie Capoulade, Laurent Gallais, Jeanyves Natoli, Mireille CommandreAbstract:We have investigated the influence of laser beam size on laser-Induced Damage threshold (LIDT) in the case of single- and multiple-shot irradiation. The study was performed on hafnia thin films deposited with various technologies (evaporation, sputtering, with or without ion assistance). LIDT measurements were carried out at 1064 nm and 12 ns with a spot size ranging from a few tens to a few hundreds of micrometers, in 1-on-1 and R-on-1 modes. These measurements were compared with simulations obtained with the statistical theory of laser-Induced Damage caused by initiating inclusions.
Zhengxiu Fan - One of the best experts on this subject based on the ideXlab platform.
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effects of annealing on laser Induced Damage threshold of tio2 sio2 high reflectors
Applied Surface Science, 2007Co-Authors: Jianke Yao, Jianda Shao, Zhengxiu FanAbstract:Abstract The mechanism of improving 1064 nm, 12 ns laser-Induced Damage threshold (LIDT) of TiO 2 /SiO 2 high reflectors (HR) prepared by electronic beam evaporation from 5.1 to 13.1 J/cm 2 by thermal annealing is discussed. Through optical properties, structure and chemical composition analysis, it is found that the reduced atomic non-stoichiometric defects are the main reason of absorption decrease and LIDT rise after annealing. A remarkable increase of LIDT is found at 300 °C annealing. The refractive index and film inhomogeneity rise, physical thickness decrease, and film stress changes from compress stress to tensile stress due to the structure change during annealing.
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high laser Induced Damage threshold hfo2 films prepared by ion assisted electron beam evaporation
Applied Surface Science, 2005Co-Authors: Shuhai Fan, Jianda Shao, Yuanan Zhao, Weidong Gao, Ruiying Fan, Yingjian Wang, Zhengxiu FanAbstract:HfO2 films were deposited by electron beam evaporation with different deposition parameters. The properties such as refractive index, weak absorption, and laser Induced Damage thresholds (LIDTs) of these films have been investigated. It was found that when pulsed Nd:YAG 1064 nm laser is used to investigate LIDT of films: Metallic character is the main factor that influences LIDTs of films obtained from Hf starting material by ion-assisted reaction, and films prepared with higher momentum transfer parameter P have fewer metallic character; The ion-assisted reaction parameters are key points for preparing high LIDT films and if the parameters are chose properly, high LIDT films can be obtained. (c) 2004 Elsevier B.V. All rights reserved.
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annealing effects on structure and laser Induced Damage threshold of ta2o5 sio2 dielectric mirrors
Applied Surface Science, 2003Co-Authors: Yuanan Zhao, Jianda Shao, Yingjian Wang, Hui Gong, Zhengxiu FanAbstract:Abstract The effects of annealing on structure and laser-Induced Damage threshold (LIDT) of Ta 2 O 5 /SiO 2 dielectric mirrors were investigated. Ta 2 O 5 /SiO 2 multilayer was prepared by ion beam sputtering (IBS), then annealed in air under the temperature from 100 to 400 °C. Microstructure of the samples was characterized by X-ray diffraction (XRD). Absorption of the multilayer was measured by surface thermal lensing (STL) technique. The laser-Induced Damage threshold was assessed using 1064 nm free pulsed laser at a pulse length of 220 μs. It was found that the center wavelength shifted to long wavelength gradually as the annealing temperature increased, and kept its non-crystalline structure even after annealing. The absorbance of the reflectors decreased after annealing. A remarkable increase of the laser-Induced Damage threshold was found when the annealing temperature was above 250 °C.
Jeanyves Natoli - One of the best experts on this subject based on the ideXlab platform.
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influence of longitudinal mode beating on laser Induced Damage in fused silica
Optics Letters, 2014Co-Authors: Romain Diaz, Maxime Chambonneau, Roger Courchinoux, P Grua, J Luce, Jeanluc Rullier, Jeanyves Natoli, Laurent LamaignereAbstract:In our study, the laser-Induced Damage densities on a fused silica surface produced by multiple longitudinal mode (MLM) pulses are found to be higher than those produced by single longitudinal mode pulses at 1064 nm. This behavior is explained by the enhancement of the three-photon absorption due to the intensity spikes related to longitudinal mode beating. At 355 nm, the absorption is linear and an opposite behavior occurs. It can be explained with the help of a process involving thermomechanics coupled with the fine time structure of MLM pulses, leading to the possible annealing of part of the absorbent defects.
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bulk laser Induced Damage threshold of titanium doped sapphire crystals
Applied Optics, 2012Co-Authors: Benoit Bussiere, Jeanyves Natoli, Mireille Commandre, O Uteza, M Sentis, N Sanner, G Riboulet, L Vigroux, Frank R Wagner, J P ChambaretAbstract:The bulk laser-Induced Damage threshold (LIDT) fluence of Ti:sapphire is determined under single-pulse irradiation from the femtosecond to nanosecond temporal regimes in the visible and near-infrared spectral domains. In the range of explored laser conditions, the LIDT fluence increases with both pulse duration and wavelength. The results are also compared to laser interaction with sapphire samples and show an increased resistance to laser Damage when the material is doped with Ti3+ ions. These conclusions are of interest for robust operation of high-peak-power femtosecond Ti:sapphire laser chains.
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model for nanosecond laser Induced Damage in potassium titanyl phosphate crystals
Applied Physics Letters, 2011Co-Authors: Frank Wagner, Anne Hildenbrand, Jeanyves Natoli, Grégoire Duchâteau, Mireille CommandreAbstract:A model for nanosecond laser Induced Damage in the bulk of potassium titanyl phosphate nonlinear optical crystals is presented. In a first step, laser-Induced Damage precursors are produced by multiphoton absorption. In a second step, the Damage precursors are activated. Damage occurs if the precursor activation rate exceeds a critical value. Basic considerations allow evaluating the parameters of the model. The validity of the model is discussed by comparing it to several experimental observations, in particular, the decrease of the laser Damage threshold during second harmonic generation of 1064 nm pulses.
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laser Induced Damage of sapphire and titanium doped sapphire crystals under femtosecond to nanosecond laser irradiation
Laser Damage Symposium XLI: Annual Symposium on Optical Materials for High Power Lasers, 2009Co-Authors: Benoit Bussiere, Jeanyves Natoli, Mireille Commandre, O Uteza, N Sanner, Marc L Sentis, G Riboulet, L Vigroux, Frank R Wagner, J P ChambaretAbstract:The use of large Ti:Sapphire crystals in ultra fast high peak power laser amplifiers makes crucial the problem of crystal laser Induced Damage. These works aim to quantify the laser Induced Damage threshold (LIDT) of Sapphire and Ti:Sapphire crystals under femtosecond, picosecond and nanosecond laser pulse irradiations, which are typically encountered in such laser chains. Furthermore, a study of the influence of cryogenic conditions on the LIDT of Ti:Sapphire crystals and of their anti-reflection coating has been performed. The results are important to understand the mechanisms leading to the Damage, and to reveal the key parameters which will have to be optimized in future high peak power laser chains.
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multiscale analysis of the laser Induced Damage threshold in optical coatings
Applied Optics, 2008Co-Authors: Jeremie Capoulade, Laurent Gallais, Jeanyves Natoli, Mireille CommandreAbstract:We have investigated the influence of laser beam size on laser-Induced Damage threshold (LIDT) in the case of single- and multiple-shot irradiation. The study was performed on hafnia thin films deposited with various technologies (evaporation, sputtering, with or without ion assistance). LIDT measurements were carried out at 1064 nm and 12 ns with a spot size ranging from a few tens to a few hundreds of micrometers, in 1-on-1 and R-on-1 modes. These measurements were compared with simulations obtained with the statistical theory of laser-Induced Damage caused by initiating inclusions.
Grégoire Duchâteau - One of the best experts on this subject based on the ideXlab platform.
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model for nanosecond laser Induced Damage in potassium titanyl phosphate crystals
Applied Physics Letters, 2011Co-Authors: Frank Wagner, Anne Hildenbrand, Jeanyves Natoli, Grégoire Duchâteau, Mireille CommandreAbstract:A model for nanosecond laser Induced Damage in the bulk of potassium titanyl phosphate nonlinear optical crystals is presented. In a first step, laser-Induced Damage precursors are produced by multiphoton absorption. In a second step, the Damage precursors are activated. Damage occurs if the precursor activation rate exceeds a critical value. Basic considerations allow evaluating the parameters of the model. The validity of the model is discussed by comparing it to several experimental observations, in particular, the decrease of the laser Damage threshold during second harmonic generation of 1064 nm pulses.
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simple models for laser Induced Damage and conditioning of potassium dihydrogen phosphate crystals by nanosecond pulses
Optics Express, 2009Co-Authors: Grégoire DuchâteauAbstract:When potassium dihydrogen phosphate crystals (KH2PO4 or KDP) are illuminated by multi-gigawatt nanosecond pulses, Damages may appear in the crystal bulk. One can increase Damage resistance through a conditioning that consists in carrying out a laser pre-exposure of the crystal. The present paper addresses the modeling of laser-Induced Damage and conditioning of KDP crystals. The method is based on heating a distribution of defects, the cooperation of which may lead to a dramatic temperature rise. In a previous investigation [Opt. Express 15, 4557-4576 (2007)], calculations were performed for cases where the heat diffusion was permitted in one and three spatial dimensions, corresponding respectively to planar and point defects. For the sake of completeness, the present study involves the 2D heat diffusion that is associated with linear defects. A comparison to experimental data leads to the conclusion that 1D calculations are the most appropriate for describing the laser-Induced Damage in KDP. Within this framework, the evolution of the Damage density is given as a function of the laser energy density and an in-depth analysis of the results is provided based on simple analytical expressions that can be used for experimental design. Regarding the conditioning, assuming that it is due to a decrease in the defect absorption efficiency, two scenarios associated with various defect natures are proposed and these account for certain of the observed experimental facts. For instance, in order to improve the crystal resistance to Damage, one needs to use a conditioning pulse duration shorter than the testing pulse. Also, a conditioning scenario based on the migration of point (atomic-size) defects allows the reproduction of a logarithmic-like evolution of the conditioning gain with respect to the number of laser pre-exposures. Moreover, this study aims at refining the knowledge regarding the precursor defects responsible for the laser-Induced Damage in KDP crystals. Within the presented modeling, the best candidate permitting the reproduction of major experimental facts is comprised of a collection of one-hundred-nanometer structural defects associated with point defects as for instance cracks and couples of oxygen interstitials and vacancies.