The removal of multi-compound protective thin PVD films for stressed industrial tools using laser ablation could enhance or replace currently used procedures. Developing a laser removal process can shorten the processing time and costs. In the first step, the laser-induced damage threshold of the thin CrAlSiN coating and the WC-Co material was measured. Nanosecond and picosecond laser pulses were used for comparison. Furthermore, the dependence of the ablated material volume and ablation depth on the fluence and the number of pulses was measured. Finally, spectral analysis of the laser plasma generated during ablation was performed.
{"title":"Laser removal of PVD coatings","authors":"Martin Mydlář, J. Vanda, Radek Poboril, J. Brajer","doi":"10.1117/12.2642743","DOIUrl":"https://doi.org/10.1117/12.2642743","url":null,"abstract":"The removal of multi-compound protective thin PVD films for stressed industrial tools using laser ablation could enhance or replace currently used procedures. Developing a laser removal process can shorten the processing time and costs. In the first step, the laser-induced damage threshold of the thin CrAlSiN coating and the WC-Co material was measured. Nanosecond and picosecond laser pulses were used for comparison. Furthermore, the dependence of the ablated material volume and ablation depth on the fluence and the number of pulses was measured. Finally, spectral analysis of the laser plasma generated during ablation was performed.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116285176","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}
The rapid deployment of high-energy laser systems has significantly pushed the practical limit of laser-induced optics damage. Most systems have chosen to scale the aperture of the laser system to operate within the damage limitations. However, most damage testing protocols do not take into consideration the sampling area of the damage testing beam with respect to the size of the extraction aperture. In this work, we review examples of laser systems where damage testing with small-scale S-on-1 results failed to predict the damage subsequently observed on a full aperture system. We provide guidance on how to adjust the post-coating damage testing protocol to gain confidence that the full-aperture optic will not be damaged during nominal high-fluence operations.
{"title":"Small-beam damage test scaling for full-aperture damage performance","authors":"Z. Liao, T. Spinka","doi":"10.1117/12.2644342","DOIUrl":"https://doi.org/10.1117/12.2644342","url":null,"abstract":"The rapid deployment of high-energy laser systems has significantly pushed the practical limit of laser-induced optics damage. Most systems have chosen to scale the aperture of the laser system to operate within the damage limitations. However, most damage testing protocols do not take into consideration the sampling area of the damage testing beam with respect to the size of the extraction aperture. In this work, we review examples of laser systems where damage testing with small-scale S-on-1 results failed to predict the damage subsequently observed on a full aperture system. We provide guidance on how to adjust the post-coating damage testing protocol to gain confidence that the full-aperture optic will not be damaged during nominal high-fluence operations.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124317298","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}
We developed a low reflective beam splitter (BS) for hot-spot monitoring of argon-fluoride (ArF) laser, and detected hot-spot in a laser beam profile only at high discharge current and high output power mode.
{"title":"Hot-spot monitoring of ArF laser at HDC and high energy mode using low reflective beam splitter","authors":"Masoud Babaeian, E. Mason, Jue Wang, G. Cox","doi":"10.1117/12.2641982","DOIUrl":"https://doi.org/10.1117/12.2641982","url":null,"abstract":"We developed a low reflective beam splitter (BS) for hot-spot monitoring of argon-fluoride (ArF) laser, and detected hot-spot in a laser beam profile only at high discharge current and high output power mode.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114899085","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}
Absorptance is often considered a static feature of an optical element that is determined via standardized measurement procedures. Although such measurements are often performed using optical instruments with low light intensity, in high power laser applications irradiation conditions are considerably different. Optics might become unstable due to highly intense light: optical properties change in a nonlinear way and might eventually lead to laser-induced damage. To study these effects we employed the common-path interferometry technique in combination with a high energy and high average power laser source, operating at 1 MHz repetition rate and delivering 10 ps pulses at 355 nm wavelength. We investigated an anti-reflective (AR@355 nm) coating deposited using ion beam sputtering on a lithium triborate (LBO) crystal. Our preliminary results indicate both strong nonlinear absorptance and fatigue near the damaging fluence, however, damage events were not directly related to the critical absorptance level. An attempt is made to predict the lifetime of an AR coated optics by establishing a numerical model of nonlinear absorption.
{"title":"Real-time investigation of the UV nonlinear absorptance in an anti-reflective coated LBO crystals","authors":"Erikas Atkočaitis, A. Melninkaitis","doi":"10.1117/12.2641222","DOIUrl":"https://doi.org/10.1117/12.2641222","url":null,"abstract":"Absorptance is often considered a static feature of an optical element that is determined via standardized measurement procedures. Although such measurements are often performed using optical instruments with low light intensity, in high power laser applications irradiation conditions are considerably different. Optics might become unstable due to highly intense light: optical properties change in a nonlinear way and might eventually lead to laser-induced damage. To study these effects we employed the common-path interferometry technique in combination with a high energy and high average power laser source, operating at 1 MHz repetition rate and delivering 10 ps pulses at 355 nm wavelength. We investigated an anti-reflective (AR@355 nm) coating deposited using ion beam sputtering on a lithium triborate (LBO) crystal. Our preliminary results indicate both strong nonlinear absorptance and fatigue near the damaging fluence, however, damage events were not directly related to the critical absorptance level. An attempt is made to predict the lifetime of an AR coated optics by establishing a numerical model of nonlinear absorption.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117235218","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}
L. Clink, Zhihan Li, C. Kuz, J. Gupta, E. Chowdhury
Laser processing is useful for topographical and band structure modification of semiconductors. We used a Scanning Tunneling Microscope (STM) to map topography and spectra around hydrofluoric acid etched silicon (100) damaged with an ultrafast pulsed Yb:KGW laser at 1030nm with duration of 70fs in high vacuum. STM uses an atomically sharp tip and feedback loop controlled piezoelectric crystals to characterize conductive surfaces with atomic resolution. With this, we have observed periodic surface structures. This information can then be used to understand the laser damage process better and eventually can be used to characterize defect formation without the presence of topographical change.
{"title":"Scanning tunneling microscopy analysis of ultrafast laser damage of single crystal silicon","authors":"L. Clink, Zhihan Li, C. Kuz, J. Gupta, E. Chowdhury","doi":"10.1117/12.2637432","DOIUrl":"https://doi.org/10.1117/12.2637432","url":null,"abstract":"Laser processing is useful for topographical and band structure modification of semiconductors. We used a Scanning Tunneling Microscope (STM) to map topography and spectra around hydrofluoric acid etched silicon (100) damaged with an ultrafast pulsed Yb:KGW laser at 1030nm with duration of 70fs in high vacuum. STM uses an atomically sharp tip and feedback loop controlled piezoelectric crystals to characterize conductive surfaces with atomic resolution. With this, we have observed periodic surface structures. This information can then be used to understand the laser damage process better and eventually can be used to characterize defect formation without the presence of topographical change.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125961597","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}
Amile N. Zaaf, H. S. Small, Tadd M. LeRocque, Andrew R. Robson, A. Manni, D. S. Hobbs
The pulsed laser induced damage threshold (LiDT) of Random Anti-Reflective (RAR) nano-textured fused silica optics has been shown to be many times higher than thin-film AR coated optics at wavelengths ranging from the near UV through the NIR. Because an RAR nano-texture is formed by a plasma etch process that removes part of the optic surface, the observed increase in damage resistance has kept track with the LiDT advances attained by low roughness super-polishing and damage pre-cursor mitigation techniques. In this work, nano-second pulse LiDT testing of RAR nano-textured optics was conducted at the deep UV wavelength of 266nm. The effect on 266nm LiDT of the uniform removal of additional surface material from fused silica optics using a dry plasma etch process was investigated. This plasma-polishing (PP), pre-RAR process was varied using fluorine-based chemistries that removed 100-300nm of material from each test surface, with surface roughness then characterized using white-light interferometry. Photothermal interferometry confirmed that no surface absorption was added by the PP, RAR, and PP-RAR plasma etching. Both standard grade, and ultra-low bulk absorption (low-OH) fused silica were included in the tests. RAR nanotextured surfaces showed an average damage threshold of 8.4 J/cm2, a level 3 times higher than a commercially available thin-film AR coated surface. Unexpected from pulsed LiDT testing at many longer wavelengths, all plasma etched surfaces exhibited less than half the damage threshold of the untreated, as-polished fused silica surfaces, and there was no observed correlation with surface roughness or plasma etch depth. From work by others it was theorized that exposure to the deep UV photons generated by the plasma might induce absorptive electronic defects in the fused silica material that could explain the reduced damage resistance relative to non-exposed surfaces. As an initial test of this concept an RAR nano-textured sample was baked at 400C to remove the suspected electronic defect. The subsequent pulsed LiDT of this one annealed sample was found to be 15.5 J/cm2, nearly double that of all other plasma etched samples. Further work to confirm this result is on-going.
{"title":"Impact of a plasma mitigation process on the 266 nm pulsed LiDT of RAR nano-textured fused silica","authors":"Amile N. Zaaf, H. S. Small, Tadd M. LeRocque, Andrew R. Robson, A. Manni, D. S. Hobbs","doi":"10.1117/12.2642768","DOIUrl":"https://doi.org/10.1117/12.2642768","url":null,"abstract":"The pulsed laser induced damage threshold (LiDT) of Random Anti-Reflective (RAR) nano-textured fused silica optics has been shown to be many times higher than thin-film AR coated optics at wavelengths ranging from the near UV through the NIR. Because an RAR nano-texture is formed by a plasma etch process that removes part of the optic surface, the observed increase in damage resistance has kept track with the LiDT advances attained by low roughness super-polishing and damage pre-cursor mitigation techniques. In this work, nano-second pulse LiDT testing of RAR nano-textured optics was conducted at the deep UV wavelength of 266nm. The effect on 266nm LiDT of the uniform removal of additional surface material from fused silica optics using a dry plasma etch process was investigated. This plasma-polishing (PP), pre-RAR process was varied using fluorine-based chemistries that removed 100-300nm of material from each test surface, with surface roughness then characterized using white-light interferometry. Photothermal interferometry confirmed that no surface absorption was added by the PP, RAR, and PP-RAR plasma etching. Both standard grade, and ultra-low bulk absorption (low-OH) fused silica were included in the tests. RAR nanotextured surfaces showed an average damage threshold of 8.4 J/cm2, a level 3 times higher than a commercially available thin-film AR coated surface. Unexpected from pulsed LiDT testing at many longer wavelengths, all plasma etched surfaces exhibited less than half the damage threshold of the untreated, as-polished fused silica surfaces, and there was no observed correlation with surface roughness or plasma etch depth. From work by others it was theorized that exposure to the deep UV photons generated by the plasma might induce absorptive electronic defects in the fused silica material that could explain the reduced damage resistance relative to non-exposed surfaces. As an initial test of this concept an RAR nano-textured sample was baked at 400C to remove the suspected electronic defect. The subsequent pulsed LiDT of this one annealed sample was found to be 15.5 J/cm2, nearly double that of all other plasma etched samples. Further work to confirm this result is on-going.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132754423","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}
G. Cole, C. Nguyen, D. Follman, G. Truong, Egbert Krause, Tobias Böhme
We outline the development of a high-power-handling deformable mirror device, based on a modified Thorlabs DMH40, employing a low-loss substrate-transferred crystalline coating as the reflective element. In standard products, this system features a metal coated (Ag or Al) 18 mm diameter × 150 μm thick BK10 glass substrate mounted to a 40-segment piezoelectric actuator, enabling Zernike compensation up to 4th order, with a peak-to-valley stroke up to ±17.6 μm. In the modified variant described here, the metal coating is replaced with a high-reflectivity (~99.998%) and low-stress (compressive, ~130 MPa) monocrystalline GaAs/AlGaAs Bragg stack transferred to the thin glass substrate via direct bonding. While maintaining similar physical performance, this custom system exhibits a substantial enhancement in power handling, with laser-induced damage tests (performed by Spica Technologies, Inc.) yielding a continuous-wave damage threshold of 75 MW/cm2 at 1070 nm with a 1/e2 spot diameter of 32.8 μm.
{"title":"A high-power-handling deformable mirror system employing crystalline coatings","authors":"G. Cole, C. Nguyen, D. Follman, G. Truong, Egbert Krause, Tobias Böhme","doi":"10.1117/12.2641048","DOIUrl":"https://doi.org/10.1117/12.2641048","url":null,"abstract":"We outline the development of a high-power-handling deformable mirror device, based on a modified Thorlabs DMH40, employing a low-loss substrate-transferred crystalline coating as the reflective element. In standard products, this system features a metal coated (Ag or Al) 18 mm diameter × 150 μm thick BK10 glass substrate mounted to a 40-segment piezoelectric actuator, enabling Zernike compensation up to 4th order, with a peak-to-valley stroke up to ±17.6 μm. In the modified variant described here, the metal coating is replaced with a high-reflectivity (~99.998%) and low-stress (compressive, ~130 MPa) monocrystalline GaAs/AlGaAs Bragg stack transferred to the thin glass substrate via direct bonding. While maintaining similar physical performance, this custom system exhibits a substantial enhancement in power handling, with laser-induced damage tests (performed by Spica Technologies, Inc.) yielding a continuous-wave damage threshold of 75 MW/cm2 at 1070 nm with a 1/e2 spot diameter of 32.8 μm.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133598605","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}
Tsion Teklemarim, C. Stolz, M. Brophy, Michael Pierce, P. Kupinski
The effect of oxygen partial pressure on the properties of Al2O3 films deposited by electron beam evaporation has been investigated through a combination of spectrophotometric and interferometric characterization techniques. As oxygen partial pressure increases, a decrease in the refractive index is observed, as well as a shift towards less tensile films once they are exposed to ambient conditions. This decrease in tensile stress was observed to be correlated with water content in the films. Increasing oxygen partial pressure during deposition improved film stoichiometry, absorption, and laser induced damage threshold (LIDT) at 351 nm.
{"title":"The influence of oxygen partial pressure on the properties of evaporated alumina thin films","authors":"Tsion Teklemarim, C. Stolz, M. Brophy, Michael Pierce, P. Kupinski","doi":"10.1117/12.2599213","DOIUrl":"https://doi.org/10.1117/12.2599213","url":null,"abstract":"The effect of oxygen partial pressure on the properties of Al2O3 films deposited by electron beam evaporation has been investigated through a combination of spectrophotometric and interferometric characterization techniques. As oxygen partial pressure increases, a decrease in the refractive index is observed, as well as a shift towards less tensile films once they are exposed to ambient conditions. This decrease in tensile stress was observed to be correlated with water content in the films. Increasing oxygen partial pressure during deposition improved film stoichiometry, absorption, and laser induced damage threshold (LIDT) at 351 nm.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114131916","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}
The potassium dihydrogen phosphate (KDP) crystals suffer from nanosecond pulse laser irradiation and are susceptible to damage during the operation of ICF system. In particular, the microcracks on the surface of KDP crystals caused by the single-point diamond fly-cutting (SPDF) process are more likely to cause serious damage under the subsequent laser irradiation. However, the mechanism of laser damage is still unclear. A model that can well represents the laser damage response is very important to reveal the mechanism of laser-induced damage. In this work, the electromagnetic field, stress field and temperature field are coupled, the mechanical characteristics of KDP material are considered, and the reasonable strength equation is applied to model the laser damage response of KDP crystal. Then, the conical crack is taken as an example to explore the laser damage response process of KDP crystal caused by surface defects under laser irradiation. It is found that the surface conical cracks have a great influence on the response process and the morphological characteristics of the laser damage. The existence of surface conical crack defects would lead to the extension of the longitudinal cracks beneath the damage crater, which has great disadvantages for the repairing of the laser damage sites. This work is of great guidance for avoiding the defects-induced damage and improving the service life of the crystal applied in ICF systems.
{"title":"Surface damage evolution of KDP crystals induced by conical cracks under irradiation of nanosecond laser","authors":"Wenyu Ding, Mingjun Chen, Jian Cheng, Hao Yang, Linjie Zhao, Qi Liu, Zhichao Liu","doi":"10.1117/12.2618820","DOIUrl":"https://doi.org/10.1117/12.2618820","url":null,"abstract":"The potassium dihydrogen phosphate (KDP) crystals suffer from nanosecond pulse laser irradiation and are susceptible to damage during the operation of ICF system. In particular, the microcracks on the surface of KDP crystals caused by the single-point diamond fly-cutting (SPDF) process are more likely to cause serious damage under the subsequent laser irradiation. However, the mechanism of laser damage is still unclear. A model that can well represents the laser damage response is very important to reveal the mechanism of laser-induced damage. In this work, the electromagnetic field, stress field and temperature field are coupled, the mechanical characteristics of KDP material are considered, and the reasonable strength equation is applied to model the laser damage response of KDP crystal. Then, the conical crack is taken as an example to explore the laser damage response process of KDP crystal caused by surface defects under laser irradiation. It is found that the surface conical cracks have a great influence on the response process and the morphological characteristics of the laser damage. The existence of surface conical crack defects would lead to the extension of the longitudinal cracks beneath the damage crater, which has great disadvantages for the repairing of the laser damage sites. This work is of great guidance for avoiding the defects-induced damage and improving the service life of the crystal applied in ICF systems.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129851019","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}
Temporal and spectral Laser-induced UV-loss studies in DUV-fibers with undoped synthetic silica core, mainly low-OH silica and modifications, were carried out with an automated set-up using pulsed 213 nm, 266 nm and 355 nm Nd-YAG Lasers. A multiple Gaussian band approximation was used to separate the individual but superimposed optically active UV defects leading to new temporal results of the individual UV defects. The curve shape of spectral losses was found to be different and strongly influenced by the Laser wavelengths, which are within absorption bands in low-OH silica, reducing the correlated defect at the beginning of irradiation significantly. In addition to solarization caused by 266 nm Laser damaging, annealing of some defects was observed. Depending on the fiber type, including hydrogen-treated types, different time constants were determined. Obvious transformations were observed during damaging with Lasers and/or broadband D2-lamp. Finally, an improved fitting of the UV attenuation or UV-induced losses in UV-fibers around 250 nm (ODC-II region) was possible by introducing two bands with slightly different peak wavelengths and temporal behaviors.
{"title":"Generation of UV-defects in UV fibers: comparison between different pulsed UV lasers","authors":"S. Heiden, P. Raithel, K. Klein, G. Hillrichs","doi":"10.1117/12.2597970","DOIUrl":"https://doi.org/10.1117/12.2597970","url":null,"abstract":"Temporal and spectral Laser-induced UV-loss studies in DUV-fibers with undoped synthetic silica core, mainly low-OH silica and modifications, were carried out with an automated set-up using pulsed 213 nm, 266 nm and 355 nm Nd-YAG Lasers. A multiple Gaussian band approximation was used to separate the individual but superimposed optically active UV defects leading to new temporal results of the individual UV defects. The curve shape of spectral losses was found to be different and strongly influenced by the Laser wavelengths, which are within absorption bands in low-OH silica, reducing the correlated defect at the beginning of irradiation significantly. In addition to solarization caused by 266 nm Laser damaging, annealing of some defects was observed. Depending on the fiber type, including hydrogen-treated types, different time constants were determined. Obvious transformations were observed during damaging with Lasers and/or broadband D2-lamp. Finally, an improved fitting of the UV attenuation or UV-induced losses in UV-fibers around 250 nm (ODC-II region) was possible by introducing two bands with slightly different peak wavelengths and temporal behaviors.","PeriodicalId":202227,"journal":{"name":"Laser Damage","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130373860","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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