Laser damage testing of ion beam sputtered (IBS) films for 1064 nm, Q-switched, low repetition rate operation typically involves the measurement of small physical defects that can be detected visually or photographically. For this kind of damage the small absorber model adequately describes most of the observations. We discuss why the damage threshold for IBS anti-reflection (AR) coatings is lower than for high reflectors and polarizers. We report on a new process technique that eliminates the physical damage to IBS AR coatings for fluences up to 21 J/cm2, possibly higher. The success of this process and the lower damage for AR's indicates that the small absorbers are at the substrate/coating interface or are in the subsurface region of the substrate. We also discuss ongoing experiments to look for subtle forms of laser damage involving changes of the optical parameters of the thin film materials, under long-term exposure to Q-switched 1064 nm radiation and continuous 355 nm radiation.
{"title":"A laser preconditioning process for improving the laser damage threshold, and the search for subtle laser damage from long-duration laser exposure for IBS thin films","authors":"Dale C. Ness, A. Streater","doi":"10.1117/12.753747","DOIUrl":"https://doi.org/10.1117/12.753747","url":null,"abstract":"Laser damage testing of ion beam sputtered (IBS) films for 1064 nm, Q-switched, low repetition rate operation typically involves the measurement of small physical defects that can be detected visually or photographically. For this kind of damage the small absorber model adequately describes most of the observations. We discuss why the damage threshold for IBS anti-reflection (AR) coatings is lower than for high reflectors and polarizers. We report on a new process technique that eliminates the physical damage to IBS AR coatings for fluences up to 21 J/cm2, possibly higher. The success of this process and the lower damage for AR's indicates that the small absorbers are at the substrate/coating interface or are in the subsurface region of the substrate. We also discuss ongoing experiments to look for subtle forms of laser damage involving changes of the optical parameters of the thin film materials, under long-term exposure to Q-switched 1064 nm radiation and continuous 355 nm radiation.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124733112","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 this paper we analyze the photo-excitation of electron sub-system of a periodic nano-structure by IR laser radiation. The nano-structure is a 1D super-lattice on surface of dielectric or semiconductor material transparent for the incident radiation. Theoretical description of the photo-excitation is based on the recent modification of the Keldysh theory adapted to the 1D case. We show that two specific regimes of the photo-excitation are possible in the super-lattices: photo-excitation suppression corresponding to decrease of the photo-excitation rate with increasing of laser intensity, and singularity regime corresponding to abrupt increase of the photo-ionization rate. Threshold of the singularity regime is calculated as function of laser wavelength and super-lattice period. The obtained results allow to propose a promising application of the super-lattices as intensity limiters for IR optical systems. In particular, we can calculate the period of the super-lattice to provide limiting of input laser intensity at required level due to multi-photon absorption by electrons of the lattice. Temperature of laser-induced heating resulted from total absorption of an incident laser pulse and diffraction distortions induced by the super-lattice are estimated to confirm possibility of utilizing the super-lattices as the intensity limiters.
{"title":"Photo-ionization of superlattices on dielectric surface by IR radiation","authors":"V. Gruzdev","doi":"10.1117/12.754056","DOIUrl":"https://doi.org/10.1117/12.754056","url":null,"abstract":"In this paper we analyze the photo-excitation of electron sub-system of a periodic nano-structure by IR laser radiation. The nano-structure is a 1D super-lattice on surface of dielectric or semiconductor material transparent for the incident radiation. Theoretical description of the photo-excitation is based on the recent modification of the Keldysh theory adapted to the 1D case. We show that two specific regimes of the photo-excitation are possible in the super-lattices: photo-excitation suppression corresponding to decrease of the photo-excitation rate with increasing of laser intensity, and singularity regime corresponding to abrupt increase of the photo-ionization rate. Threshold of the singularity regime is calculated as function of laser wavelength and super-lattice period. The obtained results allow to propose a promising application of the super-lattices as intensity limiters for IR optical systems. In particular, we can calculate the period of the super-lattice to provide limiting of input laser intensity at required level due to multi-photon absorption by electrons of the lattice. Temperature of laser-induced heating resulted from total absorption of an incident laser pulse and diffraction distortions induced by the super-lattice are estimated to confirm possibility of utilizing the super-lattices as the intensity limiters.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116101573","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 present S/1 and R/1 test results on unconditioned and 355 nm (3ω), 500 ps laser conditioned DKDP. We find up to ~2.5X improvement in fluence in the S/1 performance after 3ω, 500 ps conditioning to 5 J/cm2. For the first time, we observe a shift to higher fluences in the R/1 results for DKDP at 3ω, 7 ns due to 500 ps laser conditioning. The S/1 results are compared to ρ(Φ) results previously measured on the same DKDP crystal [1]. A consistent behavior in fluence was found between the S/1 and ρ(Φ) results for unconditioned and 500 ps conditioned DKDP. We were successful at using Poisson statistics to derive a connection between the S/1 and ρ(Φ) results that could be tested with our data sets by trying to predict the shape of the ρ(Φ) curve. The value for the power dependence on fluence of ρ(Φ) derived from the S/1 data was ~11 ± 50%. The results presented and discussed here imply a strong correlation between the damage probability (S/1) test and ρ(Φ). We find a consistent description of the two test types in terms of a power law ρ(Φ) and that this basic shape held for all cases, i.e. the shape was invariant between unconditioned and conditioned results.
{"title":"Comparison between S/1 and R/1 tests and damage density vs. fluence (ρ(Φ)) results for unconditioned and sub-nanosecond laser-conditioned KD2PO4 crystals","authors":"J. Adams, J. Jarboe, M. Feit, R. Hackel","doi":"10.1117/12.752961","DOIUrl":"https://doi.org/10.1117/12.752961","url":null,"abstract":"We present S/1 and R/1 test results on unconditioned and 355 nm (3ω), 500 ps laser conditioned DKDP. We find up to ~2.5X improvement in fluence in the S/1 performance after 3ω, 500 ps conditioning to 5 J/cm2. For the first time, we observe a shift to higher fluences in the R/1 results for DKDP at 3ω, 7 ns due to 500 ps laser conditioning. The S/1 results are compared to ρ(Φ) results previously measured on the same DKDP crystal [1]. A consistent behavior in fluence was found between the S/1 and ρ(Φ) results for unconditioned and 500 ps conditioned DKDP. We were successful at using Poisson statistics to derive a connection between the S/1 and ρ(Φ) results that could be tested with our data sets by trying to predict the shape of the ρ(Φ) curve. The value for the power dependence on fluence of ρ(Φ) derived from the S/1 data was ~11 ± 50%. The results presented and discussed here imply a strong correlation between the damage probability (S/1) test and ρ(Φ). We find a consistent description of the two test types in terms of a power law ρ(Φ) and that this basic shape held for all cases, i.e. the shape was invariant between unconditioned and conditioned results.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116291707","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}
John J. Eric, John O. Bagford, C. Devlin, R. Hull, Daniel B. Seibert
During the annual NIST calibration testing done at the LHMEL facility in FY06 on its high energy Carbon-Dioxide lasers, the LHMEL II device suffered severe damage to the internal surface of its ZnSe output coupler optics. The damage occurred during a high power, short duration run and it was believed to have been the result of a significant amount of surface contaminants interacting with the LHMEL cavity beam. Initial theories as to the source of the contamination led to the inspection of the vacuum grease that seals the piping that supplies the source gases to the laser cavity. Other contamination sources were considered, and analysis was conducted in an effort to identify the material found at the damage sites on the optic, but the tests were mainly inconclusive. Some procedure changes were initiated to identify possible contamination before high energy laser operation in an attempt to mitigate and possibly prevent the continued occurrence of damage to the output coupler window. This paper is to illustrate the type and extent of the damage encountered, highlight some of the theories as to the contamination source, and serve as a notice as to the severity and consequences of damage that is possible even due to small amounts of foreign material in a high energy laser environment.
{"title":"Optical damage observed in the LHMEL II output coupler","authors":"John J. Eric, John O. Bagford, C. Devlin, R. Hull, Daniel B. Seibert","doi":"10.1117/12.758950","DOIUrl":"https://doi.org/10.1117/12.758950","url":null,"abstract":"During the annual NIST calibration testing done at the LHMEL facility in FY06 on its high energy Carbon-Dioxide lasers, the LHMEL II device suffered severe damage to the internal surface of its ZnSe output coupler optics. The damage occurred during a high power, short duration run and it was believed to have been the result of a significant amount of surface contaminants interacting with the LHMEL cavity beam. Initial theories as to the source of the contamination led to the inspection of the vacuum grease that seals the piping that supplies the source gases to the laser cavity. Other contamination sources were considered, and analysis was conducted in an effort to identify the material found at the damage sites on the optic, but the tests were mainly inconclusive. Some procedure changes were initiated to identify possible contamination before high energy laser operation in an attempt to mitigate and possibly prevent the continued occurrence of damage to the output coupler window. This paper is to illustrate the type and extent of the damage encountered, highlight some of the theories as to the contamination source, and serve as a notice as to the severity and consequences of damage that is possible even due to small amounts of foreign material in a high energy laser environment.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114515809","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}
By coupling statistics and heat transfer, we investigate numerically laser-induced KDP crystal damage by multi-gigawatt nanosecond pulses. Our model is based on the heating of nanometric absorbing defects that may cooperate when they are sufficiently aggregated. In such a case, they induce locally a strong increase of temperature that may lead to a subsequent damage. Statistics is used to evaluate the initial defect cluster size distribution. When the crystal is illuminated, by considering in addition heat transfer processes, this approach allows to predict damage probabilities and the evolution of the damaged sites density as a function of the laser fluence. We show that the scaling law exponent, linking the critical laser fluence to its pulse duration, takes a value close to 0.3 departing from the standard 0.5 value that is in a good agreement with recents experiments. Furthermore, these results indicate that absorbers involved in KDP damage may be associated with a collection of planar defects.
{"title":"A model of laser-induced damage of KDP based on the coupling of statistics and heat transfer","authors":"G. Duchateau, A. Dyan","doi":"10.1117/12.752614","DOIUrl":"https://doi.org/10.1117/12.752614","url":null,"abstract":"By coupling statistics and heat transfer, we investigate numerically laser-induced KDP crystal damage by multi-gigawatt nanosecond pulses. Our model is based on the heating of nanometric absorbing defects that may cooperate when they are sufficiently aggregated. In such a case, they induce locally a strong increase of temperature that may lead to a subsequent damage. Statistics is used to evaluate the initial defect cluster size distribution. When the crystal is illuminated, by considering in addition heat transfer processes, this approach allows to predict damage probabilities and the evolution of the damaged sites density as a function of the laser fluence. We show that the scaling law exponent, linking the critical laser fluence to its pulse duration, takes a value close to 0.3 departing from the standard 0.5 value that is in a good agreement with recents experiments. Furthermore, these results indicate that absorbers involved in KDP damage may be associated with a collection of planar defects.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134146168","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}
B. Langdon, D. Patel, E. Krous, J. Rocca, C. Menoni, F. Tomasel, S. Kholi, P. Mccurdy, P. Langston, A. Ogloza
We investigate the variations that occur with changes in the number of layers and with the use of the assist beam main and assist beam energy on the morphology of HfO2/SiO2 quarter wave stacks deposited by dual ion beam sputtering. We show how the addition of sequential HfO2/SiO2 bilayers, up to eight, affects the surface roughness and micro-crystallinity of the top HfO2 layer. We also show that use of the assist source significantly smooths the surface while simultaneously reducing microcrystallinity. The HfO2/SiO2 structures are very robust and can withstand fluences in excess of 3 J/cm2 generated by 1ps pulses from a chirped amplified Ti:Sapphire laser.
{"title":"Influence of process conditions on the optical properties HfO2/SiO2 thin films for high power laser coatings","authors":"B. Langdon, D. Patel, E. Krous, J. Rocca, C. Menoni, F. Tomasel, S. Kholi, P. Mccurdy, P. Langston, A. Ogloza","doi":"10.1117/12.753027","DOIUrl":"https://doi.org/10.1117/12.753027","url":null,"abstract":"We investigate the variations that occur with changes in the number of layers and with the use of the assist beam main and assist beam energy on the morphology of HfO2/SiO2 quarter wave stacks deposited by dual ion beam sputtering. We show how the addition of sequential HfO2/SiO2 bilayers, up to eight, affects the surface roughness and micro-crystallinity of the top HfO2 layer. We also show that use of the assist source significantly smooths the surface while simultaneously reducing microcrystallinity. The HfO2/SiO2 structures are very robust and can withstand fluences in excess of 3 J/cm2 generated by 1ps pulses from a chirped amplified Ti:Sapphire laser.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"6720 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130399610","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 ongoing development in microlithography towards further miniaturization of structures creates a strong demand for lens material with nearly ideal optical properties. Beside the highly demanding requirements on homogeneity and stress induced birefringence (SIB), low absorption is a key factor. Even a small absorption is associated with a temperature increase and results in thermally induced local variations of refractive index and SIB. This could affect the achievable resolution of the lithographic process. The total absorption of the material is composed of initial absorption and of absorption induced during irradiation. Thus, the optimization of both improves the lifetime of the material. In principal, it is possible to measure transmission and scattering with a suitable spectrometer assembly and calculate absorption from them. However, owing to the influence of sample surfaces and errors of measurement, these methods usually do not provide satisfactory results for highly light-transmissive fused silica. Therefore, it is most desirable to find a technique that is capable of directly measuring absorption coefficients in the range of (1...10)•10-4 cm-1 (base 10) directly. We report our first results for fused silica achieved with the LID technique. Besides a fused silica grade designed for 193 nm applications, grades with higher absorption at 193 nm were measured to test the LID technique. A special focus was set on the possibility of measuring initial absorption without the influence of degradation effects.
{"title":"Measurement of initial absorption of fused silica at 193nm using laser induced deflection technique (LID)","authors":"D. Schönfeld, U. Klett, C. Mühlig, S. Thomas","doi":"10.1117/12.753081","DOIUrl":"https://doi.org/10.1117/12.753081","url":null,"abstract":"The ongoing development in microlithography towards further miniaturization of structures creates a strong demand for lens material with nearly ideal optical properties. Beside the highly demanding requirements on homogeneity and stress induced birefringence (SIB), low absorption is a key factor. Even a small absorption is associated with a temperature increase and results in thermally induced local variations of refractive index and SIB. This could affect the achievable resolution of the lithographic process. The total absorption of the material is composed of initial absorption and of absorption induced during irradiation. Thus, the optimization of both improves the lifetime of the material. In principal, it is possible to measure transmission and scattering with a suitable spectrometer assembly and calculate absorption from them. However, owing to the influence of sample surfaces and errors of measurement, these methods usually do not provide satisfactory results for highly light-transmissive fused silica. Therefore, it is most desirable to find a technique that is capable of directly measuring absorption coefficients in the range of (1...10)•10-4 cm-1 (base 10) directly. We report our first results for fused silica achieved with the LID technique. Besides a fused silica grade designed for 193 nm applications, grades with higher absorption at 193 nm were measured to test the LID technique. A special focus was set on the possibility of measuring initial absorption without the influence of degradation effects.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130946788","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}
This is a short review of the main reasons of the laser induced damage space scaling, when damage is caused by the first laser shoot (1-on-1) and by the sequence of N laser pulses to one and the same place (N-on-1). It is shown that the laser pulse shape is important to laser damage and scaling in some cases. The accumulation of material property changes and LID threshold for N-on-1 process has strong dependence on the front and on the back pulse slopes: the material property remnant changes become les and eventually accumulative damage disappears when the pulse slopes are increased. When damage scaling is defined by competition of the self-focusing and SBS processes, the long front slope is favored to SBS. The theoretical model explains damage from the first laser shot (1-on-1), damage from sequence of laser pulses (N-on-1 LID), accumulation and damage scaling. The volume damage of transparent dielectrics by laser radiation, when photon energy is more then twice less material ionization (hν
{"title":"Scaling in damage of optical materials by intensive laser radiation","authors":"E. Maldutis","doi":"10.1117/12.753827","DOIUrl":"https://doi.org/10.1117/12.753827","url":null,"abstract":"This is a short review of the main reasons of the laser induced damage space scaling, when damage is caused by the first laser shoot (1-on-1) and by the sequence of N laser pulses to one and the same place (N-on-1). It is shown that the laser pulse shape is important to laser damage and scaling in some cases. The accumulation of material property changes and LID threshold for N-on-1 process has strong dependence on the front and on the back pulse slopes: the material property remnant changes become les and eventually accumulative damage disappears when the pulse slopes are increased. When damage scaling is defined by competition of the self-focusing and SBS processes, the long front slope is favored to SBS. The theoretical model explains damage from the first laser shot (1-on-1), damage from sequence of laser pulses (N-on-1 LID), accumulation and damage scaling. The volume damage of transparent dielectrics by laser radiation, when photon energy is more then twice less material ionization (hν","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130969734","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}
A Grazing Incidence Metal Mirror (GIMM) is a chief candidate for beam delivery for Inertial Fusion Energy (IFE). The goal for GIMM survival is greater than 3×108 laser pulses with 5 J/cm2 laser fluence normal to the incident beam. Laser-induced damage to metal mirrors is primarily a thermomechanical process. Long-term exposure leads to microstructural evolution analogous to fatigue. We have performed laser-induced damage experiments on high damage threshold aluminum mirrors using commercial KrF excimer (248 nm) lasers. We have studied mirror response to standard, 25 ns long-pulses as well as to IFE prototypic, 5 ns short-pulses achieved using a Pockels Cell. Short-pulse damage fluence was found to be better than predicted using simple thermal diffusion scaling from long-pulse results.
{"title":"Effect of laser pulse duration on damage to metal mirrors for laser IFE","authors":"J. Pulsifer, M. Tillack, S. S. Harilal","doi":"10.1117/12.752940","DOIUrl":"https://doi.org/10.1117/12.752940","url":null,"abstract":"A Grazing Incidence Metal Mirror (GIMM) is a chief candidate for beam delivery for Inertial Fusion Energy (IFE). The goal for GIMM survival is greater than 3×108 laser pulses with 5 J/cm2 laser fluence normal to the incident beam. Laser-induced damage to metal mirrors is primarily a thermomechanical process. Long-term exposure leads to microstructural evolution analogous to fatigue. We have performed laser-induced damage experiments on high damage threshold aluminum mirrors using commercial KrF excimer (248 nm) lasers. We have studied mirror response to standard, 25 ns long-pulses as well as to IFE prototypic, 5 ns short-pulses achieved using a Pockels Cell. Short-pulse damage fluence was found to be better than predicted using simple thermal diffusion scaling from long-pulse results.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133596826","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 effect of electric field distribution on the laser damage probability curves of multilayer coatings is investigated. The interpretation of laser damage probability curves uses a statistical model, where shapes and slopes of the curves are related to the spot size and to the densities of nanodefects that are responsible for damage and where each kind of precursors is characterized by its damage threshold. This statistical model is improved by considering value and shape of electric field in each layer of the coating. Typical multilayer coating constituted by alternate materials of high and low index are considered. For each kind of nanoprecursors and for each fluence, the value of electric field which leads to damage is calculated. This relative threshold value permits to know with accuracy the ratio of the coating thickness where the irradiation fluence is greater than the nanoprecursor threshold and to finally estimate the appropriate laser damage probability curves.
{"title":"Effect of electric field distribution on the laser damage probability curves of multilayer coatings","authors":"H. Krol, C. Amra, C. Grèzes-besset, M. Commandré","doi":"10.1117/12.752820","DOIUrl":"https://doi.org/10.1117/12.752820","url":null,"abstract":"The effect of electric field distribution on the laser damage probability curves of multilayer coatings is investigated. The interpretation of laser damage probability curves uses a statistical model, where shapes and slopes of the curves are related to the spot size and to the densities of nanodefects that are responsible for damage and where each kind of precursors is characterized by its damage threshold. This statistical model is improved by considering value and shape of electric field in each layer of the coating. Typical multilayer coating constituted by alternate materials of high and low index are considered. For each kind of nanoprecursors and for each fluence, the value of electric field which leads to damage is calculated. This relative threshold value permits to know with accuracy the ratio of the coating thickness where the irradiation fluence is greater than the nanoprecursor threshold and to finally estimate the appropriate laser damage probability curves.","PeriodicalId":204978,"journal":{"name":"SPIE Laser Damage","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114395638","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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