V. Tarasenko, M. Erofeev, Igor D. Kostyrja, M. Lomaev, D. Rybka
Emission characteristics of a nanosecond discharge in nitrogen, inert gases and its halogenides without preionization of the gap from an auxiliary source have been investigated. A volume discharge, initiated by an avalanche electron beam (VDIAEB) was realized at pressures up to 12 atm. It has been shown that at VDIAEB excitation no less than 90% energy in the 120-850 nm range is emitted by Xe, Kr, Ar dimers. Xenon spectra in the range 120-850 nm and time-amplitude characteristics have been recorded and analyzed for various excitation regimes. In xenon at pressure of 1.2 atm, the energy of spontaneous radiation in the full solid angle was ~ 45 mJ/cm3, and the FWHM of a radiation pulse was ~ 110 ns. The spontaneous radiation power rise in xenon was observed at pressures up to 12 atm. Pulsed power densities of radiation of inert gases halogenides excited by VDIAEB was ~ 4.5 kW/cm2 at efficiency up to 5.5 %.
{"title":"Pulsed UV and VUV excilamps","authors":"V. Tarasenko, M. Erofeev, Igor D. Kostyrja, M. Lomaev, D. Rybka","doi":"10.1117/12.782585","DOIUrl":"https://doi.org/10.1117/12.782585","url":null,"abstract":"Emission characteristics of a nanosecond discharge in nitrogen, inert gases and its halogenides without preionization of the gap from an auxiliary source have been investigated. A volume discharge, initiated by an avalanche electron beam (VDIAEB) was realized at pressures up to 12 atm. It has been shown that at VDIAEB excitation no less than 90% energy in the 120-850 nm range is emitted by Xe, Kr, Ar dimers. Xenon spectra in the range 120-850 nm and time-amplitude characteristics have been recorded and analyzed for various excitation regimes. In xenon at pressure of 1.2 atm, the energy of spontaneous radiation in the full solid angle was ~ 45 mJ/cm3, and the FWHM of a radiation pulse was ~ 110 ns. The spontaneous radiation power rise in xenon was observed at pressures up to 12 atm. Pulsed power densities of radiation of inert gases halogenides excited by VDIAEB was ~ 4.5 kW/cm2 at efficiency up to 5.5 %.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133589689","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}
After an introductory overview of different types of laser propulsion schemes a review of the corresponding laser requirements will be given ranging from low power lasers sources to inertial confinement laser facilities. A subsequent status of work reveals the impasse in which the laser propulsion community is currently engaged. Revisiting the basic relations leads to new avenues in ablative and direct laser propulsion for ground based and space based applications. Hereby, special attention is devoted to the space qualification of available laser sources using a microgravity installation. A new approach to debris removal project is discussed with respect to the use Satellite Laser Ranging (SRL) facilities. Finally, a novel aspect for direct photon propulsion in space is derived by introducing the concept of a "long" optical resonator. Potential and limits of this concept are presented opening the possibility of photon propulsion over 100 km path under realistic experimental conditions.
{"title":"Novel aspects in laser propulsion","authors":"W. Bohn","doi":"10.1117/12.785634","DOIUrl":"https://doi.org/10.1117/12.785634","url":null,"abstract":"After an introductory overview of different types of laser propulsion schemes a review of the corresponding laser requirements will be given ranging from low power lasers sources to inertial confinement laser facilities. A subsequent status of work reveals the impasse in which the laser propulsion community is currently engaged. Revisiting the basic relations leads to new avenues in ablative and direct laser propulsion for ground based and space based applications. Hereby, special attention is devoted to the space qualification of available laser sources using a microgravity installation. A new approach to debris removal project is discussed with respect to the use Satellite Laser Ranging (SRL) facilities. Finally, a novel aspect for direct photon propulsion in space is derived by introducing the concept of a \"long\" optical resonator. Potential and limits of this concept are presented opening the possibility of photon propulsion over 100 km path under realistic experimental conditions.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132239874","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 Laser and Optics Research Center of the US Air Force Academy started a research program on optically pumped alkali lasers in 2004. We demonstrated the first diode pumped alkali (cesium) vapor laser, the first optically pumped potassium laser, the most efficient (slope efficiency higher than 80%) cesium laser, and diode pumped Rb and Cs lasers with highest output powers (17 W and 48 W respectively). We have developed an efficient Cs amplifier with a small signal amplification factor of 145 and tunable single mode Cs laser for scientific applications. In this paper we present a review of our main results and recent achievements in high power alkali laser development, discuss some problems existing in this field and ways to solve them.
{"title":"Alkali lasers development at Laser and Optics Research Center of the U.S. Air Force Academy","authors":"B. Zhdanov, R. Knize","doi":"10.1117/12.782846","DOIUrl":"https://doi.org/10.1117/12.782846","url":null,"abstract":"The Laser and Optics Research Center of the US Air Force Academy started a research program on optically pumped alkali lasers in 2004. We demonstrated the first diode pumped alkali (cesium) vapor laser, the first optically pumped potassium laser, the most efficient (slope efficiency higher than 80%) cesium laser, and diode pumped Rb and Cs lasers with highest output powers (17 W and 48 W respectively). We have developed an efficient Cs amplifier with a small signal amplification factor of 145 and tunable single mode Cs laser for scientific applications. In this paper we present a review of our main results and recent achievements in high power alkali laser development, discuss some problems existing in this field and ways to solve them.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130566344","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}
Sheng-Nian Luo, S. Greenfield, D. Paisley, Randall P. Johnson, T. Shimada, D. Byler, Eric Loomis, S. Digiacomo, S. Digiacomo, Brian M. Patterson, K. Mcclellan, Robert M. Dickerson, Pedro Peralta, A. Koskelo, D. Tonks
We present two laser driven shock wave loading techniques utilizing long pulse lasers, laser-launched flyer plate and confined laser ablation, and their applications to shock physics. The full width at half maximum of the drive laser pulse ranges from 100 ns to 10 μs, and its energy, from 10 J to 1000 J. The drive pulse is smoothed with a holographic optical element to achieve spatial homogeneity in loading. We characterize the flyer plate during flight and dynamically loaded target with temporally and spatially resolved diagnostics. The long duration and high energy of the drive pulse allow for shockless acceleration of thick flyer plates with 8 mm diameter and 0.1-2 mm thickness. With transient imaging displacement interferometry and line-imaging velocimetry, we demonstrate that the planarity (bow and tilt) of the loading is within 2-7 mrad (with an average of 4±1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible in particular when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation enables flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These dynamic loading techniques using long pulse lasers (0.1-10 μs) along with short pulse lasers (1-10 ns) can be an accurate, versatile and efficient complement to conventional shock wave loading for investigating such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples, in a wide range of strain rates and pressures at meso- and macroscopic scales.
{"title":"Long pulse laser driven shock wave loading for dynamic materials experiments","authors":"Sheng-Nian Luo, S. Greenfield, D. Paisley, Randall P. Johnson, T. Shimada, D. Byler, Eric Loomis, S. Digiacomo, S. Digiacomo, Brian M. Patterson, K. Mcclellan, Robert M. Dickerson, Pedro Peralta, A. Koskelo, D. Tonks","doi":"10.1117/12.782206","DOIUrl":"https://doi.org/10.1117/12.782206","url":null,"abstract":"We present two laser driven shock wave loading techniques utilizing long pulse lasers, laser-launched flyer plate and confined laser ablation, and their applications to shock physics. The full width at half maximum of the drive laser pulse ranges from 100 ns to 10 μs, and its energy, from 10 J to 1000 J. The drive pulse is smoothed with a holographic optical element to achieve spatial homogeneity in loading. We characterize the flyer plate during flight and dynamically loaded target with temporally and spatially resolved diagnostics. The long duration and high energy of the drive pulse allow for shockless acceleration of thick flyer plates with 8 mm diameter and 0.1-2 mm thickness. With transient imaging displacement interferometry and line-imaging velocimetry, we demonstrate that the planarity (bow and tilt) of the loading is within 2-7 mrad (with an average of 4±1 mrad), similar to that in conventional techniques including gas gun loading. Plasma heating of target is negligible in particular when a plasma shield is adopted. For flyer plate loading, supported shock waves can be achieved. Temporal shaping of the drive pulse in confined laser ablation enables flexible loading, e.g., quasi-isentropic, Taylor-wave, and off-Hugoniot loading. These dynamic loading techniques using long pulse lasers (0.1-10 μs) along with short pulse lasers (1-10 ns) can be an accurate, versatile and efficient complement to conventional shock wave loading for investigating such dynamic responses of materials as Hugoniot elastic limit, plasticity, spall, shock roughness, equation of state, phase transition, and metallurgical characteristics of shock-recovered samples, in a wide range of strain rates and pressures at meso- and macroscopic scales.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"49 11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121195897","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 are focused on the understanding the underlying physical mechanisms of femtosecond laser interactions with metallic and multi-layer optical materials. The results of the numerical modeling provide an estimation of damage and/or ablation threshold for different laser parameters (pulse duration, fluence, angle of incidence, polarization) and target material properties (metal, dielectric, or multilayer with variable metal layer thickness). These results are compared with the experimental measurements of the thresholds obtained by using different techniques. In particular, dielectric ionization and ablation mechanisms are analyzed based on the experimental findings.
{"title":"Ultra-short laser interaction with metals and optical multi-layer materials: transport phenomena and damage thresholds","authors":"T. Itina, O. Uteza, N. Sanner, M. Sentis","doi":"10.1117/12.782263","DOIUrl":"https://doi.org/10.1117/12.782263","url":null,"abstract":"In this paper, we are focused on the understanding the underlying physical mechanisms of femtosecond laser interactions with metallic and multi-layer optical materials. The results of the numerical modeling provide an estimation of damage and/or ablation threshold for different laser parameters (pulse duration, fluence, angle of incidence, polarization) and target material properties (metal, dielectric, or multilayer with variable metal layer thickness). These results are compared with the experimental measurements of the thresholds obtained by using different techniques. In particular, dielectric ionization and ablation mechanisms are analyzed based on the experimental findings.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121421362","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 concept of high energy density (HED) radiation driven momentum coupling (momentum transfer), CM, to a targets in a vacuum is analytically developed and applied via successive plasma, ablative, and hydrodynamic interfaces undergoing both weak and strong shocks. CM are derived from equations of state (EOS) variables and serve as figures of merit to determine energy efficiency conversion into target momentum. Generally, CM are proportional to the inverse of the interaction speed and related variables for each interaction regime. This approach provides a formalism allowing computation of hitherto intractable HED radiation and mechanical momentum coupling interactions encountered in astrophysics, planetary physics, inertial confinement fusion, near-Earth object hazard mitigation, and HED explosives modeling. CM is generally not scale invariant as are the hydrodynamic Euler equations. This analytic procedure supports interpretation of experiments using EOS response of material targets to HED interactions on the meso - and macro-scales to describe CM.
{"title":"Laser radiation plasma dynamics and momentum coupling","authors":"J. Remo","doi":"10.1117/12.781905","DOIUrl":"https://doi.org/10.1117/12.781905","url":null,"abstract":"The concept of high energy density (HED) radiation driven momentum coupling (momentum transfer), CM, to a targets in a vacuum is analytically developed and applied via successive plasma, ablative, and hydrodynamic interfaces undergoing both weak and strong shocks. CM are derived from equations of state (EOS) variables and serve as figures of merit to determine energy efficiency conversion into target momentum. Generally, CM are proportional to the inverse of the interaction speed and related variables for each interaction regime. This approach provides a formalism allowing computation of hitherto intractable HED radiation and mechanical momentum coupling interactions encountered in astrophysics, planetary physics, inertial confinement fusion, near-Earth object hazard mitigation, and HED explosives modeling. CM is generally not scale invariant as are the hydrodynamic Euler equations. This analytic procedure supports interpretation of experiments using EOS response of material targets to HED interactions on the meso - and macro-scales to describe CM.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115689638","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}
Tatsunori Sakano, Ryo Nishimura, H. Fukuoka, Y. Yata, T. Saiki, M. Obara, H. Kato, M. Sano
We investigate post-annealing effects using an epi-GaN substrates for ZnO thin film growth by pulsed laser deposition (PLD). The growth of ZnO nanorods on a Si(100) substrate through a two-step process, annealing and off-axis PLD, without a metal catalyst is demonstrated as well. The as-grown films were annealed for one hour under atmospheric pressure air. ZnO morphologies after annealing were measured and the post-annealed ZnO films grown at Tg = 700oC had very smooth surfaces and the rms roughness was about 0.5 nm. Finally, ZnO post-annealed buffer layer was inserted between ZnO epi-layer and GaN/sapphire substrates. It was evident by AFM that growth temperature of 700oC helps the films grow in a step-flow growth mode. It was confirmed by cathode luminescence (CL) spectrum that the ZnO film grown at 700oC had very low visible luminescence, resulting in a decrease of the deep level defects. In the case of ZnO nanorods, controlling growth parameters during deposition enabled the adjustment of the dimensions of nanorods. The diameters of the grown nanorods ranged from 50 to 700 nm and the lengths are from 2 to 10 μm. The CL spectra were used to evaluate the states of defects within the ZnO nanorods. According to the CL results, the thinnest nanorod arrays were found to have fewer defects, while more defects were introduced as nanorods became thicker.
{"title":"ZnO thin film and nanorod growth by pulsed laser deposition for photonic devices","authors":"Tatsunori Sakano, Ryo Nishimura, H. Fukuoka, Y. Yata, T. Saiki, M. Obara, H. Kato, M. Sano","doi":"10.1117/12.785224","DOIUrl":"https://doi.org/10.1117/12.785224","url":null,"abstract":"We investigate post-annealing effects using an epi-GaN substrates for ZnO thin film growth by pulsed laser deposition (PLD). The growth of ZnO nanorods on a Si(100) substrate through a two-step process, annealing and off-axis PLD, without a metal catalyst is demonstrated as well. The as-grown films were annealed for one hour under atmospheric pressure air. ZnO morphologies after annealing were measured and the post-annealed ZnO films grown at Tg = 700oC had very smooth surfaces and the rms roughness was about 0.5 nm. Finally, ZnO post-annealed buffer layer was inserted between ZnO epi-layer and GaN/sapphire substrates. It was evident by AFM that growth temperature of 700oC helps the films grow in a step-flow growth mode. It was confirmed by cathode luminescence (CL) spectrum that the ZnO film grown at 700oC had very low visible luminescence, resulting in a decrease of the deep level defects. In the case of ZnO nanorods, controlling growth parameters during deposition enabled the adjustment of the dimensions of nanorods. The diameters of the grown nanorods ranged from 50 to 700 nm and the lengths are from 2 to 10 μm. The CL spectra were used to evaluate the states of defects within the ZnO nanorods. According to the CL results, the thinnest nanorod arrays were found to have fewer defects, while more defects were introduced as nanorods became thicker.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"7005 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129666948","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}
Ultrafast intense femtosecond laser pulses spontaneously undergo critical collapse in air and condensed media above some critical power. In normally dispersive media, such pulses can spontaneously generate dynamical X-waves where distinct X-features appear in the spectrally-resolved far-field. These nonlinear self-trapped pulses resemble linear Bessel beams - the latter exhibit extended line rather than point foci and are robust to strong perturbations. Nonlinear X-waves can be directly generated by using an axicon lens and have the potential to generate highly nonlinear, extended interaction zones relative to pulses with Gaussian profiles. Potential applications of these pulsed sources to controlling and extending white light supercontinuum and plasma channel generation will be discussed. X-wave generation in normally dispersive media is associated witha cascade of pulse splittings where individual split pulses have been identified with different arms of the spectrally observed X-feature. This allows for novel pump-probe experiments where a seed pulse can selectively generate Raman Stokes shifted waves by scattering off of different arms of the X-feature. We will discuss a 3-wave interaction picture that allows for a transparent physical interpretation of these complex spatio-temporal events.
{"title":"Nonlinear ultrafast femtosecond X-waves","authors":"J. Moloney, M. Kolesik","doi":"10.1117/12.783463","DOIUrl":"https://doi.org/10.1117/12.783463","url":null,"abstract":"Ultrafast intense femtosecond laser pulses spontaneously undergo critical collapse in air and condensed media above some critical power. In normally dispersive media, such pulses can spontaneously generate dynamical X-waves where distinct X-features appear in the spectrally-resolved far-field. These nonlinear self-trapped pulses resemble linear Bessel beams - the latter exhibit extended line rather than point foci and are robust to strong perturbations. Nonlinear X-waves can be directly generated by using an axicon lens and have the potential to generate highly nonlinear, extended interaction zones relative to pulses with Gaussian profiles. Potential applications of these pulsed sources to controlling and extending white light supercontinuum and plasma channel generation will be discussed. X-wave generation in normally dispersive media is associated witha cascade of pulse splittings where individual split pulses have been identified with different arms of the spectrally observed X-feature. This allows for novel pump-probe experiments where a seed pulse can selectively generate Raman Stokes shifted waves by scattering off of different arms of the X-feature. We will discuss a 3-wave interaction picture that allows for a transparent physical interpretation of these complex spatio-temporal events.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"7005 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128760677","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}
K. Nowak, T. Suganuma, A. Endo, A. Sumitani, D. A. Goryachkin, N. A. Romanov, V. E. Sherstobitov, L. V. Kovalchuk, A. Rodionov
Recent studies of fundamental issues of target material format and laser radiation parameters have revealed the attractiveness of LPP EUV source technology based on Sn target and multi-kW CO2 laser driver. In recent work we have reported 8kW of average power at 100kHz repetition frequency and 20ns pulse duration produced by our MOPA CO2 laser driver built on a chain of Fast Axial Flow (FAF) amplifiers. However, the oscillator power is insufficient to saturate the input stages and significant amount of available laser energy (>80%) is untapped. In this paper we report a step towards an improvement of laser driver power and efficiency. For the first time, to our knowledge, the performance of a novel multi-pass pre-amplifier based on RF-excited slab waveguide CO2 laser technology has been numerically modeled. The calculations show the feasibility of this approach. We carried out amplification experiments to validate the numerical model. In our experiments we have obtained power gain of 10 at 13-pass configuration from a slab of 60x600mm2 geometry at 20ns pulse length and 100kHz repetition frequency at diffraction-limited output and no self-oscillation. The experiment has validated the numerical model, which will be used at this stage to design and optimize a pre-amplifier for our current FAF amplifier chain. Furthermore, these results enable us to design and optimize next generation of LPP laser driver based entirely on compact slab-waveguide amplifiers.
{"title":"Efficient and compact short pulse MOPA system for laser-produced-plasma extreme-UV sources employing RF-discharge slab-waveguide CO2 amplifiers","authors":"K. Nowak, T. Suganuma, A. Endo, A. Sumitani, D. A. Goryachkin, N. A. Romanov, V. E. Sherstobitov, L. V. Kovalchuk, A. Rodionov","doi":"10.1117/12.782606","DOIUrl":"https://doi.org/10.1117/12.782606","url":null,"abstract":"Recent studies of fundamental issues of target material format and laser radiation parameters have revealed the attractiveness of LPP EUV source technology based on Sn target and multi-kW CO2 laser driver. In recent work we have reported 8kW of average power at 100kHz repetition frequency and 20ns pulse duration produced by our MOPA CO2 laser driver built on a chain of Fast Axial Flow (FAF) amplifiers. However, the oscillator power is insufficient to saturate the input stages and significant amount of available laser energy (>80%) is untapped. In this paper we report a step towards an improvement of laser driver power and efficiency. For the first time, to our knowledge, the performance of a novel multi-pass pre-amplifier based on RF-excited slab waveguide CO2 laser technology has been numerically modeled. The calculations show the feasibility of this approach. We carried out amplification experiments to validate the numerical model. In our experiments we have obtained power gain of 10 at 13-pass configuration from a slab of 60x600mm2 geometry at 20ns pulse length and 100kHz repetition frequency at diffraction-limited output and no self-oscillation. The experiment has validated the numerical model, which will be used at this stage to design and optimize a pre-amplifier for our current FAF amplifier chain. Furthermore, these results enable us to design and optimize next generation of LPP laser driver based entirely on compact slab-waveguide amplifiers.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"330 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124655086","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 CW diode-pumped alkali laser (DPAL) based on the D1 rubidium resonance transition has been investigated. The pump sources for these experiments are two 780 nm fiber-coupled diode modules, incorporating volume holographic gratings for wavelength control. Total pump power is up to 64 W. Rb laser output at the 794.8 nm fundamental wavelength is up to 7.8 W. Intracavity second harmonic generation in BIBO generates up to 250 mW at 397.4 nm.
{"title":"Second harmonic operation of diode-pumped Rb vapor lasers","authors":"A. Petersen, R. Lane","doi":"10.1117/12.784984","DOIUrl":"https://doi.org/10.1117/12.784984","url":null,"abstract":"A CW diode-pumped alkali laser (DPAL) based on the D1 rubidium resonance transition has been investigated. The pump sources for these experiments are two 780 nm fiber-coupled diode modules, incorporating volume holographic gratings for wavelength control. Total pump power is up to 64 W. Rb laser output at the 794.8 nm fundamental wavelength is up to 7.8 W. Intracavity second harmonic generation in BIBO generates up to 250 mW at 397.4 nm.","PeriodicalId":249315,"journal":{"name":"High-Power Laser Ablation","volume":"80 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120864797","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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