M. Mureșan, J. Vanda, Saulius Pakalnis, Martin Mydlář, J. Brajer
With numerous manufacturers providing different laser-induced damage threshold (LIDT) values in the nanosecond regime, a simple ranking based on numbers alone may not provide a clear picture of the best choice. Variations in testing procedures, albeit following the ISO 21254 standard, further complicate the selection process. By employing a comprehensive 1-on-1 test procedure, it becomes possible to observe various parameters that influence LIDT values. When sharing test results within the community, adhering to good practices and meticulous attention to the error budget and its contributors are crucial. Above all, laser optics users must comprehend the intricacies of laser-induced damage testing and seek detailed information instead of relying solely on numerical comparisons. This study explores the challenges and considerations in selecting and testing laser optics, emphasizing the importance of a comprehensive approach.
由于众多制造商提供的纳秒级激光诱导损伤阈值（LIDT）各不相同，仅根据数字进行简单的排序可能无法清楚地说明最佳选择。尽管测试程序遵循 ISO 21254 标准，但其中的差异使选择过程更加复杂。通过采用全面的 1 对 1 测试程序，可以观察到影响 LIDT 值的各种参数。在社区内共享测试结果时，遵守良好的操作规范、仔细关注误差预算及其影响因素至关重要。最重要的是，激光光学用户必须了解激光诱导损伤测试的复杂性，并寻求详细信息，而不是仅仅依赖数字比较。本研究探讨了选择和测试激光光学器件的挑战和注意事项，强调了综合方法的重要性。
{"title":"Influence of laser beam size on the determination of LIDT","authors":"M. Mureșan, J. Vanda, Saulius Pakalnis, Martin Mydlář, J. Brajer","doi":"10.1117/12.2686177","DOIUrl":"https://doi.org/10.1117/12.2686177","url":null,"abstract":"With numerous manufacturers providing different laser-induced damage threshold (LIDT) values in the nanosecond regime, a simple ranking based on numbers alone may not provide a clear picture of the best choice. Variations in testing procedures, albeit following the ISO 21254 standard, further complicate the selection process. By employing a comprehensive 1-on-1 test procedure, it becomes possible to observe various parameters that influence LIDT values. When sharing test results within the community, adhering to good practices and meticulous attention to the error budget and its contributors are crucial. Above all, laser optics users must comprehend the intricacies of laser-induced damage testing and seek detailed information instead of relying solely on numerical comparisons. This study explores the challenges and considerations in selecting and testing laser optics, emphasizing the importance of a comprehensive approach.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139242494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jae Hyuck Yoo, Yoonsoo Rho, Christopher F. Miller, Robin E. Yancey, Ted A. Laurence, C. W. Carr
We present a temporally and spatially resolved photoluminescence (PL) measurement technique developed to rapidly characterize fused silica damage sites and determine their propensity to grow under subsequent laser irradiation. A diffusional model is used to describe the observed PL dynamics and correlation to the local damage morphologies. We believe that our measurement and analysis approach can allow rapid identification of growth-prone damage sites, providing a pathway to fast, non-destructive predictions of laser-induced damage growth and enable selective damage site mitigation which will greatly reduce the time required to recycle NIF’s optics.
{"title":"Temporally and spatially resolved photoluminescence of laser-induced damage sites of fused silica","authors":"Jae Hyuck Yoo, Yoonsoo Rho, Christopher F. Miller, Robin E. Yancey, Ted A. Laurence, C. W. Carr","doi":"10.1117/12.2683719","DOIUrl":"https://doi.org/10.1117/12.2683719","url":null,"abstract":"We present a temporally and spatially resolved photoluminescence (PL) measurement technique developed to rapidly characterize fused silica damage sites and determine their propensity to grow under subsequent laser irradiation. A diffusional model is used to describe the observed PL dynamics and correlation to the local damage morphologies. We believe that our measurement and analysis approach can allow rapid identification of growth-prone damage sites, providing a pathway to fast, non-destructive predictions of laser-induced damage growth and enable selective damage site mitigation which will greatly reduce the time required to recycle NIF’s optics.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alex Ribeaud, Jürgen Pistner, Mathias Soulier, Julien Lumeau, Laurent Gallais, Rico Benz, Christoph Sturzenegger, B. Eiermann, Christian Mühlig, Thomas Gischkat, Sven Schröder
In many laser applications, there is a higher and higher demand for more efficient coatings with reduced losses, in terms of absorption and scattering as those are contributing factors to diverse laser damage regimes. Ion Beam Sputtering (IBS) is a known technique to provide such high optical quality thin films. Indeed, it allows to achieve high density layers with low absorption and scattering. In this work, various coatings were developed using Bühler IBS technology. Then, total losses were measured using Cavity Ring Down, absorption using Laser Induced Deflection or Laser thermography, and Total Integrated Scatter using dedicated scatterometers. A correlation between the effect of the chosen deposition method and parameters and the measurement performances were made with the aim of a better understanding of the level and the origin of losses in the coatings. Finally, highly reflecting mirror coatings for 1064 nm wavelength were fabricated with different designs and deposition parameters. The results of the different measurements of absorption, scattering and total losses using different equipment are presented and discussed.
{"title":"Study of high-performance IBS coatings for near-IR laser applications","authors":"Alex Ribeaud, Jürgen Pistner, Mathias Soulier, Julien Lumeau, Laurent Gallais, Rico Benz, Christoph Sturzenegger, B. Eiermann, Christian Mühlig, Thomas Gischkat, Sven Schröder","doi":"10.1117/12.2685243","DOIUrl":"https://doi.org/10.1117/12.2685243","url":null,"abstract":"In many laser applications, there is a higher and higher demand for more efficient coatings with reduced losses, in terms of absorption and scattering as those are contributing factors to diverse laser damage regimes. Ion Beam Sputtering (IBS) is a known technique to provide such high optical quality thin films. Indeed, it allows to achieve high density layers with low absorption and scattering. In this work, various coatings were developed using Bühler IBS technology. Then, total losses were measured using Cavity Ring Down, absorption using Laser Induced Deflection or Laser thermography, and Total Integrated Scatter using dedicated scatterometers. A correlation between the effect of the chosen deposition method and parameters and the measurement performances were made with the aim of a better understanding of the level and the origin of losses in the coatings. Finally, highly reflecting mirror coatings for 1064 nm wavelength were fabricated with different designs and deposition parameters. The results of the different measurements of absorption, scattering and total losses using different equipment are presented and discussed.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jue Wang, Gerald P. Cox, Keith J. Donohue, Ronald W. Davis, Ying Shi, Cody V. Cushman, A. Rezikyan, Galan G. Moore, James E. Tingley, Keith J. Becken, Matthew R. Ross, Michael D. Thomas
Laser-induced damage (LID) tests were conducted on CaF2 optics at 193 nm using ISO S-on-1 method with the S varying from a standard 200 to 103, 104, and 105 shots/site and fluences ranging from 0.1 J/cm2 to 4.0 J/cm2. Using a flat-top beam profile and a beam footprint of 250 μm × 250 μm, absorption-derived LID was observed on the standard 200-on-1 test. Defect-initiated LID was detected by increasing the pulse count with a reduced fluence. The absorption-driven LID was attribute to subsurface damage and two-photon absorption. The former was eliminated by using a FemtoFinish polishing process. The latter was experimentally determined by using laser calorimetric measurement. Improved crystal bulk and surface finishing quality were confirmed by X-ray diffraction and laser calorimetric measurement. Accelerated lifetime damage test (ALDT) was further conducted with an increased pulse count up to 106 shots/site. The results confirm an enhanced lifespan prediction of the demanding laser optics.
{"title":"Laser-induced damage of CaF2 optics at 193 nm","authors":"Jue Wang, Gerald P. Cox, Keith J. Donohue, Ronald W. Davis, Ying Shi, Cody V. Cushman, A. Rezikyan, Galan G. Moore, James E. Tingley, Keith J. Becken, Matthew R. Ross, Michael D. Thomas","doi":"10.1117/12.2685720","DOIUrl":"https://doi.org/10.1117/12.2685720","url":null,"abstract":"Laser-induced damage (LID) tests were conducted on CaF2 optics at 193 nm using ISO S-on-1 method with the S varying from a standard 200 to 103, 104, and 105 shots/site and fluences ranging from 0.1 J/cm2 to 4.0 J/cm2. Using a flat-top beam profile and a beam footprint of 250 μm × 250 μm, absorption-derived LID was observed on the standard 200-on-1 test. Defect-initiated LID was detected by increasing the pulse count with a reduced fluence. The absorption-driven LID was attribute to subsurface damage and two-photon absorption. The former was eliminated by using a FemtoFinish polishing process. The latter was experimentally determined by using laser calorimetric measurement. Improved crystal bulk and surface finishing quality were confirmed by X-ray diffraction and laser calorimetric measurement. Accelerated lifetime damage test (ALDT) was further conducted with an increased pulse count up to 106 shots/site. The results confirm an enhanced lifespan prediction of the demanding laser optics.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139241165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isaac L. Bass, Eyal Feigenbaum, James Vickers, Gabriel Guss, W. Carr
Cones machined into the surface of the final fused silica optics on the NIF have been used to remove laser induced damage from exposure to high fluence 351 nm laser light. When applied to the input surface of an optic, a shadow is created on the exit surface due to the divergence of the laser light by the cone walls. In recent years input surface cones have been utilized to shadow exit surface damage and thus arrest its continued growth. The expanding waves from the cone walls interfere with the incident beam to create a high fluence intensification at the exit surface. This intensification has the characteristic periodic spatial variation on a scale of the order of the 351 nm wavelength. The question arises as to how the damage density probability, ρ(Φ), is affected by this variation as compared to a uniform fluence. Does it follow the local periodic variation, or is it averaged over that variation. We consider both cases, how it can be predicted by direct measurement of the intensification as opposed to costly damage tests, and how we might measure the effect directly.
{"title":"Characterization of micron scale periodic fluence variation and its possible impact on laser damage","authors":"Isaac L. Bass, Eyal Feigenbaum, James Vickers, Gabriel Guss, W. Carr","doi":"10.1117/12.2685137","DOIUrl":"https://doi.org/10.1117/12.2685137","url":null,"abstract":"Cones machined into the surface of the final fused silica optics on the NIF have been used to remove laser induced damage from exposure to high fluence 351 nm laser light. When applied to the input surface of an optic, a shadow is created on the exit surface due to the divergence of the laser light by the cone walls. In recent years input surface cones have been utilized to shadow exit surface damage and thus arrest its continued growth. The expanding waves from the cone walls interfere with the incident beam to create a high fluence intensification at the exit surface. This intensification has the characteristic periodic spatial variation on a scale of the order of the 351 nm wavelength. The question arises as to how the damage density probability, ρ(Φ), is affected by this variation as compared to a uniform fluence. Does it follow the local periodic variation, or is it averaged over that variation. We consider both cases, how it can be predicted by direct measurement of the intensification as opposed to costly damage tests, and how we might measure the effect directly.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139239585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Surface damage of silica optics routinely limits the operation of high energy laser systems. Initiated damage can grow upon additional laser pulses, eventually requiring optic removal/replacement. However, when damage is first initiated, small damage sites grow in a stochastic manner, readily parameterized by the size of the damage site, surface of residence, and the fluence and pulse duration of subsequent laser exposures. The National Ignition Facility (NIF), which exposes ~100 m2 of fused silica optics surface to high-energy-nanosecond-laser light on every full system shot, provides an ideal platform to study the growth behavior of laser-induced damage. High-resolution microscopy of individual damage sites is captured as part of the standard NIF recycling loop. However, not all damage sites are repaired depending on the age and quality of the host optic leaving many thousands sub-50-micron damages sites to resume growth after being imaged. By measuring such sites each time an optic is removed for recycling, high-resolution microscopy becomes available for many thousands of sites before and after exposure to various shot sequences on the NIF laser. Using this observed growth, a multi-shot description was fit to predict the likelihood of exit surface damage site growth under exposure from 3ω, nanosecond regime pulses for shot sequence lengths between 1-100 laser exposures. This provides a basis for accurately predicting when a recycled optic will require additional repair.
{"title":"Study of the probability of growth of silica exit surface damage on the National Ignition Facility (NIF) final optics","authors":"Christopher F. Miller, Ryan M. Gini, C. W. Carr","doi":"10.1117/12.2688143","DOIUrl":"https://doi.org/10.1117/12.2688143","url":null,"abstract":"Surface damage of silica optics routinely limits the operation of high energy laser systems. Initiated damage can grow upon additional laser pulses, eventually requiring optic removal/replacement. However, when damage is first initiated, small damage sites grow in a stochastic manner, readily parameterized by the size of the damage site, surface of residence, and the fluence and pulse duration of subsequent laser exposures. The National Ignition Facility (NIF), which exposes ~100 m2 of fused silica optics surface to high-energy-nanosecond-laser light on every full system shot, provides an ideal platform to study the growth behavior of laser-induced damage. High-resolution microscopy of individual damage sites is captured as part of the standard NIF recycling loop. However, not all damage sites are repaired depending on the age and quality of the host optic leaving many thousands sub-50-micron damages sites to resume growth after being imaged. By measuring such sites each time an optic is removed for recycling, high-resolution microscopy becomes available for many thousands of sites before and after exposure to various shot sequences on the NIF laser. Using this observed growth, a multi-shot description was fit to predict the likelihood of exit surface damage site growth under exposure from 3ω, nanosecond regime pulses for shot sequence lengths between 1-100 laser exposures. This provides a basis for accurately predicting when a recycled optic will require additional repair.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhihan Li, L. Clink, C. Kuz, Jay A. Gupta, Enam Chowdhury
A novel instrumentation design and operation to study ultrafast laser damage with atomic scale characterization by scanning tunneling microscopy is described here. The STM system operates in an ultrahigh vacuum chamber, fitted with an in situ objective allowing for tight focusing of laser excitation onto the sample. A combination of in situ and ex situ laser machining is used to define fiducial registry markers that help identify the overlap region for the optical excitation and STM scanning, aided by simultaneous confocal imaging and far-field cameras. We report initial measurements of laser damage on silicon in UHV with 10 pulses (77 fs compressed width, 0.67J/cm2 peak fluence) from a 1030nm Yb:KGW laser. STM imaging of damage sites show several characteristic regions with sharply defined boundaries determined by underlying damage thresholds, including an ablation crater and the beginnings of periodic surface structures.
{"title":"In-situ scanning tunneling microscopy of ultrafast laser damage on Si (100) surface in ultra-high vacuum","authors":"Zhihan Li, L. Clink, C. Kuz, Jay A. Gupta, Enam Chowdhury","doi":"10.1117/12.2685136","DOIUrl":"https://doi.org/10.1117/12.2685136","url":null,"abstract":"A novel instrumentation design and operation to study ultrafast laser damage with atomic scale characterization by scanning tunneling microscopy is described here. The STM system operates in an ultrahigh vacuum chamber, fitted with an in situ objective allowing for tight focusing of laser excitation onto the sample. A combination of in situ and ex situ laser machining is used to define fiducial registry markers that help identify the overlap region for the optical excitation and STM scanning, aided by simultaneous confocal imaging and far-field cameras. We report initial measurements of laser damage on silicon in UHV with 10 pulses (77 fs compressed width, 0.67J/cm2 peak fluence) from a 1030nm Yb:KGW laser. STM imaging of damage sites show several characteristic regions with sharply defined boundaries determined by underlying damage thresholds, including an ablation crater and the beginnings of periodic surface structures.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In general, there are just a few numbers of available dielectric materials suitable to produce laser optics. Such binary dielectric films are limited by fixed optical properties e.g. index of refraction and intrinsic laser induced damage threshold (LIDT). Optical properties of dielectric layers need to be manipulated precisely for further improvement. One approach is given by the deposition of ternary composites. The other approach is well known for crystalline materials and takes benefit of quantized effects. In the last years it could be shown that such effects can be utilized in amorphous dielectric layers as well. As a major benefit quantized nanolaminates enable the possibility to keep the index of refraction high with improved optical band gap. This proceeding gives an overview about key experiments of manufactured dielectric quantized nanolaminate samples and its advantages compared to ternary composites.
{"title":"Dielectric quantized nanolaminates for laser optics","authors":"Thomas Willemsen","doi":"10.1117/12.2685241","DOIUrl":"https://doi.org/10.1117/12.2685241","url":null,"abstract":"In general, there are just a few numbers of available dielectric materials suitable to produce laser optics. Such binary dielectric films are limited by fixed optical properties e.g. index of refraction and intrinsic laser induced damage threshold (LIDT). Optical properties of dielectric layers need to be manipulated precisely for further improvement. One approach is given by the deposition of ternary composites. The other approach is well known for crystalline materials and takes benefit of quantized effects. In the last years it could be shown that such effects can be utilized in amorphous dielectric layers as well. As a major benefit quantized nanolaminates enable the possibility to keep the index of refraction high with improved optical band gap. This proceeding gives an overview about key experiments of manufactured dielectric quantized nanolaminate samples and its advantages compared to ternary composites.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139241660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jue Wang, L. Wamboldt, Ronald W. Davis, Ying Shi, Todd L. Heck, Craig Ungaro, A. B. Ruffin, Michael D. Thomas
Laser-induced damage threshold (LIDT) tests were performed at 1064 nm and 20 ns. Nodule defects were identified as the LIDT-limiting factor. The results suggest that the scale of the nodules is associated with the size of defects residing on the aluminum substrate surface. 3D finite-difference time-domain (FDTD) simulation was employed to calculate the electric field intensity (EFI) enhancement at the nodular defects with a seed diameter ranging from 0.35 μm to 2.5 μm. A direct linkage between the EFI enhancement and laser-induced damage morphology was established. Additional LIDT tests were conducted on surface modified aluminum substrate by using Corning aluminum process (CAP). The surface modification led to a 10x increase of the LIDT. Finally, LIDT of the multiband mirrors was predicted based on the absorption-driven damage and defect-driven damage. The results suggested that a combination of the CAP-modified Al6061 and low defect deposition process of the dielectric enhanced layers lead to high laser durability.
{"title":"Laser-induced damage of dielectric-enhanced surface-modified single-point-diamond-turned Al-6061 multiband mirrors","authors":"Jue Wang, L. Wamboldt, Ronald W. Davis, Ying Shi, Todd L. Heck, Craig Ungaro, A. B. Ruffin, Michael D. Thomas","doi":"10.1117/12.2685665","DOIUrl":"https://doi.org/10.1117/12.2685665","url":null,"abstract":"Laser-induced damage threshold (LIDT) tests were performed at 1064 nm and 20 ns. Nodule defects were identified as the LIDT-limiting factor. The results suggest that the scale of the nodules is associated with the size of defects residing on the aluminum substrate surface. 3D finite-difference time-domain (FDTD) simulation was employed to calculate the electric field intensity (EFI) enhancement at the nodular defects with a seed diameter ranging from 0.35 μm to 2.5 μm. A direct linkage between the EFI enhancement and laser-induced damage morphology was established. Additional LIDT tests were conducted on surface modified aluminum substrate by using Corning aluminum process (CAP). The surface modification led to a 10x increase of the LIDT. Finally, LIDT of the multiband mirrors was predicted based on the absorption-driven damage and defect-driven damage. The results suggested that a combination of the CAP-modified Al6061 and low defect deposition process of the dielectric enhanced layers lead to high laser durability.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139238855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Free space communications between ground stations and geostationary satellites offer high-speed and secure data transmission, but compensating for atmospheric absorption poses a significant challenge. The need for high levels of beam power to overcome atmospheric losses calls for optics that can withstand strong flux, especially in the continuous wave (CW) regime. In this context, the absorption of optics at 1.5 µm is a critical parameter that must be accurately measured and understood to develop efficient and reliable photonic systems. This study focuses on the absorption of optical coatings at 1570 nm. Lock-In Thermography (LIT) has been developed to measure the total absorption of the coatings with high sensitivity under 1 ppm. A modulated 100 W CW laser is used to induce heating into the coating stack, and the resulting rise in internal temperature is measured with a thermal camera. The LIT experimental setup offers a non-destructive and non-contact measurement technique, making it ideal for assessing the absorption of delicate thin-film coatings. To understand the photo induced effects in a stack of thin film layers subjected to high-power laser heating, a finite element model is developed using COMSOL. The model simulates the index and thickness variations of each layer and predicts the shift in optical function resulting from photo induced effects. The results offer valuable insights into the impact of laser-induced heating on the optical properties of the coatings and provide guidelines for designing robust and reliable photonic systems.
{"title":"Measurement of optical coatings absorption at 1570 nm and simulations of photo-induced modifications of spectral function under high power laser exposure","authors":"Mathias Soulier, Laurent Gallais, Julien Lumeau, H. Krol, Emilie Steck, Mathieu Boutillier","doi":"10.1117/12.2685174","DOIUrl":"https://doi.org/10.1117/12.2685174","url":null,"abstract":"Free space communications between ground stations and geostationary satellites offer high-speed and secure data transmission, but compensating for atmospheric absorption poses a significant challenge. The need for high levels of beam power to overcome atmospheric losses calls for optics that can withstand strong flux, especially in the continuous wave (CW) regime. In this context, the absorption of optics at 1.5 µm is a critical parameter that must be accurately measured and understood to develop efficient and reliable photonic systems. This study focuses on the absorption of optical coatings at 1570 nm. Lock-In Thermography (LIT) has been developed to measure the total absorption of the coatings with high sensitivity under 1 ppm. A modulated 100 W CW laser is used to induce heating into the coating stack, and the resulting rise in internal temperature is measured with a thermal camera. The LIT experimental setup offers a non-destructive and non-contact measurement technique, making it ideal for assessing the absorption of delicate thin-film coatings. To understand the photo induced effects in a stack of thin film layers subjected to high-power laser heating, a finite element model is developed using COMSOL. The model simulates the index and thickness variations of each layer and predicts the shift in optical function resulting from photo induced effects. The results offer valuable insights into the impact of laser-induced heating on the optical properties of the coatings and provide guidelines for designing robust and reliable photonic systems.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139240344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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