A high-beam-quality diode-pumped neodymium-doped yttrium aluminum garnet(Nd:YAG) active mirror laser amplifier was demonstrated. The size of the Nd:YAG crystal was 48 mm × 42 mm × 11 mm with 0.6 at.% Nd dope...A high-beam-quality diode-pumped neodymium-doped yttrium aluminum garnet(Nd:YAG) active mirror laser amplifier was demonstrated. The size of the Nd:YAG crystal was 48 mm × 42 mm × 11 mm with 0.6 at.% Nd doped. When the pump energy was 26.8 J and the input energy was 0.3 J, the output pulse energy reached 5.4 J, and the pulse width of 11.3 ns at a 5 Hz repetition rate was obtained for the two gain modules in three-pass amplification, with corresponding optical-to-optical efficiency of 21.2%. The beam quality was measured as M_x^2=2.48 and M_y^2=2.43 in horizontal and vertical directions, respectively.展开更多
We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temper...We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temperature profile of the gain medium and the focal length of the induced thermal lens are determined numerically.The influence of the repetition rate and pumping power on the temperature distribution is analyzed.Experimental measurements covered repetition rates between 1 and 10 Hz and up to 4 kW pumping power.展开更多
We report on the energetic and beam quality performance of the second to the last main amplifier section HEPA I of the PENELOPE laser project. A polarization coupled double-12-pass scheme to verify the full amplificat...We report on the energetic and beam quality performance of the second to the last main amplifier section HEPA I of the PENELOPE laser project. A polarization coupled double-12-pass scheme to verify the full amplification capacity of the last two amplifiers HEPA I and II was used. The small signal gain for a narrow-band continuous wave laser was 900 and 527 for a broadband nanosecond pulse, demonstrating 12.6 J of output pulse energy. Those pulses, being spectrally wide enough to support equivalent 150 fs long ultrashort pulses, are shown with an excellent spatial beam quality. A first active correction of the wavefront using a deformable mirror resulted in a Strehl ratio of 76% in the single-12-pass configuration for HEPA I.展开更多
We report on the successful demonstration of a 150 J nanosecond pulsed cryogenic gas cooled,diode-pumped multi-slab Yb:YAG laser operating at 1 Hz.To the best of our knowledge,this is the highest energy ever recorded ...We report on the successful demonstration of a 150 J nanosecond pulsed cryogenic gas cooled,diode-pumped multi-slab Yb:YAG laser operating at 1 Hz.To the best of our knowledge,this is the highest energy ever recorded for a diodepumped laser system.展开更多
Optical damages, which severely degrade the output energy performance of Nd:glass regenerative amplifiers, are discussed in detail in this paper. By a series of experiments, it has been confirmed that these damages re...Optical damages, which severely degrade the output energy performance of Nd:glass regenerative amplifiers, are discussed in detail in this paper. By a series of experiments, it has been confirmed that these damages result from laser-induced contamination. Based on this work, several improvements are made to boost output energy performance of the regenerative amplifier. The output energy of the regenerative amplifier after improvements declines 4% after 1000 h of operation, much less than it used to, 60% after 560 h of operation.展开更多
Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz re...Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz repetition rate(0.75 kW average power) are reviewed. These pulses are compressed resulting in the generation of ~5 ps duration,1 J pulses with 0.5 kW average power. A full characterization of this high power cryogenic amplifier, including atwavelength interferometry of the active region under >1 kW average power pump conditions, is presented. An initial demonstration of operation at 1 kW average power(1 J, 1 k Hz) is reported.展开更多
We report on a high-repetition-rate,high-power continuously pumped Nd:GdVO4 regenerative amplifier.Numerical simulations successfully pinpoint the optimum working point free of bifurcation instability with simultaneou...We report on a high-repetition-rate,high-power continuously pumped Nd:GdVO4 regenerative amplifier.Numerical simulations successfully pinpoint the optimum working point free of bifurcation instability with simultaneous efficient energy extraction.At a repetition rate of 100 kHz,a maximum output power of 23 W was obtained with a pulse duration of 27 ps,corresponding to a pulse energy of 230 μJ.The system displayed an outstanding stability with a root mean square power noise as low as 0.3%.The geometry of the optical resonator and the pumping scheme enhanced output power in the TEM00 mode with a single bulk crystal.Accordingly,nearly diffraction-limited beam quality was produced with M2≈1.2 at full pump power.展开更多
Thermal profile modification of an active material in a laser amplifier via optical pumping results in a change in the material’s refractive index,and causes thermal expansion and stress,eventually leading to spatial...Thermal profile modification of an active material in a laser amplifier via optical pumping results in a change in the material’s refractive index,and causes thermal expansion and stress,eventually leading to spatial phase aberrations,or even permanent material damage.For this purpose,knowledge of the 3D spatio-temporal thermal profile,which can currently only be retrieved via numerical simulations,is critical for joule-class laser amplifiers to reveal potentially dangerous thermal features within the pumped active materials.In this investigation,a detailed,spatio-temporal numerical simulation was constructed and tested for accuracy against surface thermal measurements of various endpumped Yb^3+-doped laser-active materials.The measurements and simulations show an excellent agreement and the model was successfully applied to a joule-class Yb3+-based amplifier currently operating in the POLARIS laser system at the Friedrich-Schiller-University and Helmholtz-Institute Jena in Germany.展开更多
This study experimentally investigated a Yb： YAG pulse laser amplifier with a high amplification gain and a high signal-to-noise ratio （SNR）. The highest amplification gain of 172 and highest pulse energy of 131 mJ...This study experimentally investigated a Yb： YAG pulse laser amplifier with a high amplification gain and a high signal-to-noise ratio （SNR）. The highest amplification gain of 172 and highest pulse energy of 131 mJ were obtained with the highest SNR of 24.9 dB from a volume gain of 10 mm × 10 mm × 1 mm. The output beam quality values ofM2 = 1.91 in the slow axis and M2 = 1.58 in the fast axis were also achieved.展开更多
In this paper we review the design and development of a 100 J, 10 Hz nanosecond pulsed laser, codenamed DiPOLE100 X,being built at the Central Laser Facility(CLF). This 1 kW average power diode-pumped solid-state lase...In this paper we review the design and development of a 100 J, 10 Hz nanosecond pulsed laser, codenamed DiPOLE100 X,being built at the Central Laser Facility(CLF). This 1 kW average power diode-pumped solid-state laser(DPSSL) is based on a master oscillator power amplifier(MOPA) design, which includes two cryogenic gas cooled amplifier stages based on DiPOLE multi-slab ceramic Yb:YAG amplifier technology developed at the CLF. The laser will produce pulses between 2 and 15 ns in duration with precise, arbitrarily selectable shapes, at pulse repetition rates up to 10 Hz, allowing real-time shape optimization for compression experiments. Once completed, the laser will be delivered to the European X-ray Free Electron Laser(XFEL) facility in Germany as a UK-funded contribution in kind, where it will be used to study extreme states of matter at the High Energy Density(HED) instrument.展开更多
The Laboratory for Intense Lasers(L2I) is a research centre in optics and lasers dedicated to experimental research in high intensity laser science and technology and laser plasma interaction. Currently the laboratory...The Laboratory for Intense Lasers(L2I) is a research centre in optics and lasers dedicated to experimental research in high intensity laser science and technology and laser plasma interaction. Currently the laboratory is undergoing an upgrade with the goal of increasing the versatility of the laser systems available to the users, as well as increasing the pulse repetition rate. In this paper we review the current status of the laser research and development programme of this facility, namely the upgraded capability and the recent progress towards the installation of an ultrashort, diode-pumped OPCPA laser system.展开更多
文摘A high-beam-quality diode-pumped neodymium-doped yttrium aluminum garnet(Nd:YAG) active mirror laser amplifier was demonstrated. The size of the Nd:YAG crystal was 48 mm × 42 mm × 11 mm with 0.6 at.% Nd doped. When the pump energy was 26.8 J and the input energy was 0.3 J, the output pulse energy reached 5.4 J, and the pulse width of 11.3 ns at a 5 Hz repetition rate was obtained for the two gain modules in three-pass amplification, with corresponding optical-to-optical efficiency of 21.2%. The beam quality was measured as M_x^2=2.48 and M_y^2=2.43 in horizontal and vertical directions, respectively.
基金This work is partially supported by the Fundacao para a Ciencia e a Tecnologia(grant agreement No.PD/BD/135222/2017)has been carried out within the framework of Laserlab-Portugal(National Roadmap of Research Infrastructures,22124)the European Union Horizon 2020 research and innovation program under grant agreement No.654148 Laserlab-Europe.
文摘We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temperature profile of the gain medium and the focal length of the induced thermal lens are determined numerically.The influence of the repetition rate and pumping power on the temperature distribution is analyzed.Experimental measurements covered repetition rates between 1 and 10 Hz and up to 4 kW pumping power.
基金funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No.654148 Laserlab-Europe
文摘We report on the energetic and beam quality performance of the second to the last main amplifier section HEPA I of the PENELOPE laser project. A polarization coupled double-12-pass scheme to verify the full amplification capacity of the last two amplifiers HEPA I and II was used. The small signal gain for a narrow-band continuous wave laser was 900 and 527 for a broadband nanosecond pulse, demonstrating 12.6 J of output pulse energy. Those pulses, being spectrally wide enough to support equivalent 150 fs long ultrashort pulses, are shown with an excellent spatial beam quality. A first active correction of the wavefront using a deformable mirror resulted in a Strehl ratio of 76% in the single-12-pass configuration for HEPA I.
文摘We report on the successful demonstration of a 150 J nanosecond pulsed cryogenic gas cooled,diode-pumped multi-slab Yb:YAG laser operating at 1 Hz.To the best of our knowledge,this is the highest energy ever recorded for a diodepumped laser system.
基金supported by National Natural Science Foundation of China under Grant No.61405211
文摘Optical damages, which severely degrade the output energy performance of Nd:glass regenerative amplifiers, are discussed in detail in this paper. By a series of experiments, it has been confirmed that these damages result from laser-induced contamination. Based on this work, several improvements are made to boost output energy performance of the regenerative amplifier. The output energy of the regenerative amplifier after improvements declines 4% after 1000 h of operation, much less than it used to, 60% after 560 h of operation.
基金supported by the U.S. Department of Energy Accelerator Stewardship programme, Office of High Energy Physics, Office of Science under award DE-SC0016136support by the U.S. Department of Energy, Office of Science SBIR programme under award DE-SC0011375
文摘Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz repetition rate(0.75 kW average power) are reviewed. These pulses are compressed resulting in the generation of ~5 ps duration,1 J pulses with 0.5 kW average power. A full characterization of this high power cryogenic amplifier, including atwavelength interferometry of the active region under >1 kW average power pump conditions, is presented. An initial demonstration of operation at 1 kW average power(1 J, 1 k Hz) is reported.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(MOST)(No.2017YFB0405202)
文摘We report on a high-repetition-rate,high-power continuously pumped Nd:GdVO4 regenerative amplifier.Numerical simulations successfully pinpoint the optimum working point free of bifurcation instability with simultaneous efficient energy extraction.At a repetition rate of 100 kHz,a maximum output power of 23 W was obtained with a pulse duration of 27 ps,corresponding to a pulse energy of 230 μJ.The system displayed an outstanding stability with a root mean square power noise as low as 0.3%.The geometry of the optical resonator and the pumping scheme enhanced output power in the TEM00 mode with a single bulk crystal.Accordingly,nearly diffraction-limited beam quality was produced with M2≈1.2 at full pump power.
基金funding from the European Union’s Horizon 2020 Research and Innovation Programme (LASERLAB-EUROPE, Grant No. 654148)from the European Union (EFRE) through the Thuringian Ministry for Economic Affairs, Science and Digital Society (2016FE9058)from the Bundesministerium für Bildung und Forschung (BMBF) (03ZIK445, 05P15SJFA1, 03Z1H531 and 03VNE2068D)
文摘Thermal profile modification of an active material in a laser amplifier via optical pumping results in a change in the material’s refractive index,and causes thermal expansion and stress,eventually leading to spatial phase aberrations,or even permanent material damage.For this purpose,knowledge of the 3D spatio-temporal thermal profile,which can currently only be retrieved via numerical simulations,is critical for joule-class laser amplifiers to reveal potentially dangerous thermal features within the pumped active materials.In this investigation,a detailed,spatio-temporal numerical simulation was constructed and tested for accuracy against surface thermal measurements of various endpumped Yb^3+-doped laser-active materials.The measurements and simulations show an excellent agreement and the model was successfully applied to a joule-class Yb3+-based amplifier currently operating in the POLARIS laser system at the Friedrich-Schiller-University and Helmholtz-Institute Jena in Germany.
文摘This study experimentally investigated a Yb： YAG pulse laser amplifier with a high amplification gain and a high signal-to-noise ratio （SNR）. The highest amplification gain of 172 and highest pulse energy of 131 mJ were obtained with the highest SNR of 24.9 dB from a volume gain of 10 mm × 10 mm × 1 mm. The output beam quality values ofM2 = 1.91 in the slow axis and M2 = 1.58 in the fast axis were also achieved.
基金funded by the NEWTON China–UK Joint Research Project on Laser-driven Ion Acceleration and Novel Terahertz Radiation
文摘In this paper we review the design and development of a 100 J, 10 Hz nanosecond pulsed laser, codenamed DiPOLE100 X,being built at the Central Laser Facility(CLF). This 1 kW average power diode-pumped solid-state laser(DPSSL) is based on a master oscillator power amplifier(MOPA) design, which includes two cryogenic gas cooled amplifier stages based on DiPOLE multi-slab ceramic Yb:YAG amplifier technology developed at the CLF. The laser will produce pulses between 2 and 15 ns in duration with precise, arbitrarily selectable shapes, at pulse repetition rates up to 10 Hz, allowing real-time shape optimization for compression experiments. Once completed, the laser will be delivered to the European X-ray Free Electron Laser(XFEL) facility in Germany as a UK-funded contribution in kind, where it will be used to study extreme states of matter at the High Energy Density(HED) instrument.
基金supported by Fundao para a Ciência e a Tecnologia,Laserlab-Europe(EC’s FP7,grant agreement no.284464)funding from the Euratom research and training programme 2014–2018 under grant agreement No 633053
文摘The Laboratory for Intense Lasers(L2I) is a research centre in optics and lasers dedicated to experimental research in high intensity laser science and technology and laser plasma interaction. Currently the laboratory is undergoing an upgrade with the goal of increasing the versatility of the laser systems available to the users, as well as increasing the pulse repetition rate. In this paper we review the current status of the laser research and development programme of this facility, namely the upgraded capability and the recent progress towards the installation of an ultrashort, diode-pumped OPCPA laser system.
