Frequency doubling of multi-terawatt picosecond pulses

The frequency-doubling efficiency and resultant focal spot quality of a large aperture (140 × 89 mm) subpicosecond, chirped pulse amplified (CPA) 1054-nm beam for laser–matter interaction studies has been investigated using the Vulcan Nd:glass laser system (Danson et al. 1998). The effect of B-integral on the CPA beam quality was studied and is shown not to be the dominant cause of the observed frequency-doubled beam break-up. Conversion efficiency tests were carried out on small aperture KDP (type 1) crystals at a range of incident intensities up to 3 × 1011 W/cm2 giving the optimum crystal thickness for pulses in the 0.3–3 ps region. A large-aperture frequency-doubled beam was commissioned and delivered pulses of over 10 TW onto target for an electron acceleration experiment.

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1178 J, 527 nm near diffraction limited laser based on a complete closed-loop adaptive optics controlled off-axis multi-pass amplification laser system

High Power Laser Science and Engineering ◽

10.1017/hpl.2021.3 ◽

2021 ◽

Vol 9 ◽

Author(s):

Deen Wang ◽

Xin Zhang ◽

Wanjun Dai ◽

Ying Yang ◽

Xuewei Deng ◽

...

Keyword(s):

Laser Beam ◽

Adaptive Optics ◽

Closed Loop ◽

Focal Spot ◽

Beam Quality ◽

Laser System ◽

Diffraction Limit ◽

Kdp Crystal ◽

Main Amplifier

Abstract A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics (AO) controlled off-axis multi-pass amplification laser system. Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier, a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62% conversion efficiency, 1178 J and beam quality of 7.93 times the diffraction limit (DL). By using a complete closed-loop AO configuration, the static and dynamic wavefront distortions of the laser system are measured and compensated. After correction, the diameter of the circle enclosing 80% energy is improved remarkably from 7.93DL to 1.29DL. The focal spot is highly concentrated and the 1178 J, 527 nm near diffraction limited laser is achieved.

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Observations on microthermal fluctuations

Symposium - International Astronomical Union ◽

10.1017/s0074180900051834 ◽

1963 ◽

Vol 19 ◽

pp. 126-131

Author(s):

C. R. Lynds

Keyword(s):

Thermal Structure ◽

Image Motion ◽

Visual Images ◽

Image Size ◽

Large Telescope ◽

Small Aperture ◽

Large Aperture ◽

Low Levels ◽

A Site

The concern has been expressed many times by Dr. Bowen and others that a significant portion of the seeing deterioration may occur in levels of the atmosphere very near the ground, within a few tenths of meters of the ground. When I refer to the quality of seeing I am refering to the image size one observes in a telescope of very large aperture and I will assume that this is equivalent to image motion as observed in telescopes of very small aperture. I will not attempt a further justification for this concern; however this is the basis for the studies we are just beginning at Kitt Peak, where we will attempt to quantitatively show whether or not there is need for concern about the very low levels of the atmosphere. So we begin with the thesis that much of the poor seeing observed at a site, the enlargement of photographic or visual images as observed through a large telescope, is due to refractive inhomogeneities in the lower levels of the atmosphere, within less than 100 m above the telescope. We presume that these inhomogeneities are of local origin and that their distribution and motion is determined primarily by site topography, wind direction and velocity. The few experiments we have made thus far at Kitt Peak have been designed to ascertain quantitatively the importance of these factors. Our approach has been to make observations of the large-aperture seeing with simultaneous observations of the thermal structure of the air accessible to us immediately above the telescope.

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Frequency doubling multi-terawatt sub-picosecond pulses for plasma interactions

Laser and Particle Beams ◽

10.1017/s0263034600183089 ◽

2000 ◽

Vol 18 (3) ◽

pp. 405-409 ◽

Cited By ~ 5

Author(s):

D. NEELY ◽

R.M. ALLOTT ◽

R.J. CLARKE ◽

J.L. COLLIER ◽

C.N. DANSON ◽

...

Keyword(s):

Beam Quality ◽

Pulse Length ◽

Frequency Doubling ◽

Diffraction Limit ◽

High Quality ◽

Plasma Interactions ◽

Picosecond Pulses ◽

Matter Interaction ◽

Laser Facility ◽

Kdp Crystals

Frequency doubling a 140 × 110 mm 40 J sub-ps 1054 nm beam for laser matter interaction studies was investigated at the Central Laser Facility, with efficiencies greater than 60% being achieved. The conversion characteristics (efficiency, beam quality, focusability, and pulse length) for two large 157 mm diameter aperture high quality KDP crystals of thickness 2 mm and 4 mm were studied. Using a fundamental drive beam of two times diffraction limited quality, focal spots of four times the diffraction limit in the frequency doubled beam were achieved and beam degradation effects shown to be minimal.

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Research on Thermal-Effect and Phase Properties of a Q-Switched Laser Using KTP Frequency-Doubling Crystal

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.282-283.505 ◽

2011 ◽

Vol 282-283 ◽

pp. 505-508

Author(s):

Xiang Zhang

Keyword(s):

Thermal Effect ◽

Matrix Theory ◽

Beam Quality ◽

Frequency Doubling ◽

Wavefront Aberration ◽

Output Beam ◽

Ratio Curve ◽

Thermal Lens Effect ◽

Coma Aberration

Results of an experimental and theoretical analysis of the proprerties of a LD pumped laser using a plano-concave stable resonator and KTP frequency-doubling crystal material are presented. The influence of thermal lens effect on laser output mode and beam quality has been discussed briefly by using the transfer matrix theory. In this paper, further experiment on the output beam quality of a LD pumped acousto-optic Q-switched laser has been also performed by adopting Hartmann-Shack wavefront sensor and Zernike mode reconstruction theory. Using this method, the PV and RMS values of the aberration wavefront, the frontal 35-order Zernike aberrations can be acquired, and the Strehl ratio curve of the output beam and the distribution of circle energy can also be obtained by calculation, so the mode properities can be fully understood. The experimental results show that the beam wavefront aberration is mainly concentrated in the frontal 15 orders of Zernike aberration, mainly including the defocus A3, the low-order astigmatism A4 and A5, and the coma aberration A6 and A7 because of crystal thermal effect.

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Hundred-Joule-level, nanosecond-pulse Nd:glass laser system with high spatiotemporal beam quality

High Power Laser Science and Engineering ◽

10.1017/hpl.2016.2 ◽

2016 ◽

Vol 4 ◽

Cited By ~ 21

Author(s):

Sensen Li ◽

Yulei Wang ◽

Zhiwei Lu ◽

Lei Ding ◽

Yi Chen ◽

...

Keyword(s):

Pulse Width ◽

Frequency Conversion ◽

Beam Quality ◽

Laser System ◽

Energy Output ◽

Level Energy ◽

Beam Diameter ◽

System Operating ◽

Nd:Glass Laser

A 100-J-level Nd:glass laser system in nanosecond-scale pulse width has been constructed to perform as a standard source of high-fluence-laser science experiments. The laser system, operating with typical pulse durations of 3–5 ns and beam diameter 60 mm, employs a sequence of successive rod amplifiers to achieve 100-J-level energy at 1053 nm at 3 ns. The frequency conversion can provide energy of 50-J level at 351 nm. In addition to the high stability of the energy output, the most valuable of the laser system is the high spatiotemporal beam quality of the output, which contains the uniform square pulse waveform, the uniform flat-top spatial fluence distribution and the uniform flat-top wavefront.

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Beam-shaping technique for fiber-coupled diode laser system by homogenizing the beam quality of two laser diode stacks

Optics & Laser Technology ◽

10.1016/j.optlastec.2019.105919 ◽

2020 ◽

Vol 123 ◽

pp. 105919

Author(s):

Guyi Lin ◽

Pengfei Zhao ◽

Zhiyong Dong ◽

Xuechun Lin

Keyword(s):

Diode Laser ◽

Laser Diode ◽

Beam Quality ◽

Laser System ◽

Beam Shaping ◽

Shaping Technique

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A High Peak Power and High Beam Quality Sub-Nanosecond Nd:YVO4 Laser System at 1 kHz Repetition Rate without SRS Process

Applied Sciences ◽

10.3390/app9235247 ◽

2019 ◽

Vol 9 (23) ◽

pp. 5247

Author(s):

Yutao Huang ◽

Hongbo Zhang ◽

Xiaochao Yan ◽

Zhijun Kang ◽

Fuqiang Lian ◽

...

Keyword(s):

Peak Power ◽

Stimulated Raman Scattering ◽

Beam Quality ◽

Laser System ◽

Average Power ◽

Green Light ◽

Frequency Doubling ◽

High Peak ◽

High Peak Power ◽

Maximum Output

We present a compact sub-nanosecond diode-end-pumped Nd:YVO 4 laser system running at 1 kHz. A maximum output energy of 65.4 mJ without significant stimulated Raman scattering (SRS) process was obtained with a pulse duration of 600 ps, corresponding to a pulse peak power of 109 MW. Laser pulses from this system had good beam quality, where M 2 < 1.6, and the excellent signal to noise ratio was more than 42 dB. By frequency doubling with an LBO crystal, 532 nm green light with an average power of 40.5 W and a power stability of 0.28% was achieved. The diode-end-pumped pump power limitation on a high peak power amplifier caused by the SRS process and thermal fracture in bulk Nd:YVO 4 crystal is also analyzed.

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