Neodymium glass laser with a phase conjugate mirror producing 220 J pulses at 002 Hz repetition rate

Abstract

For pumping multipetawatt Ti:sapphire laser facilities we developed a compact repetitively pulsed laser based on neodymium phosphate glass with pulse energy of 220 J, pulse repetition rate of 0.02 Hz, beam diameter of 43 mm, aperture fill factor of 0.8, and FWHM pulse duration of 30 ns. The phase distortions of laser radiation were compensated by optical phase conjugation via stimulated Brillouin scattering. The depolarization was reduced to 0.4% using linear compensation methods. The beam quality was 2.5 x diffraction limit (150 µrad).

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

“…Among the main amplifier systems, most of these mediumscale lasers use Nd:glass rod amplification cascade [25][26][27][28]33] and a few of them use a combination of rod and disk amplifiers [23,32] or pure multi-slab amplifiers [34][35][36] . In our opinion, rod active elements also have good prospects.…”

“…In these medium-scale laser systems, spatial beam-shaping methods generating flat-top fluence distributions in the output near field have been investigated, such as image relaying with spatial filtering [23][24][25][26][27][28][31][32][33] , stimulated Brillouin scattering phase conjugation mirrors (SBS-PCMs) [27] , Gaussian mirror output coupler in the oscillator [25] , circular aperture selecting the quasi-uniform intensity region at the center of the expanded beam [31] and diffractive optical element (DOE) [26] . However, these are all passive shaping methods used for particular laser system, which is not suitable for achieving high spatial beam quality in complex high-power lasers applied in accurate physics experiments.…”

“…In the front-end system, some lasers use Q-switched Nd:YAG or Nd:YLF crystal master oscillators, which generate several tens to hundreds of millijoule level pulses with a duration of tens of nanoseconds (full width at half maximum) [23,[25][26][27][28]32] . However, such master oscillators make it difficult to control the pulse shape and spectrum.…”

“…The uniform wavefront is an important part of the beam quality for high-power lasers. Two wavefront shaping methods have been employed in these medium-scale laser systems, including SBS-PCMs [27, 28] and photo-controlled deformable mirror (DM) in HiLASE recently. However, SBS-PCM is a passive method for wavefront shaping and it is used as a cavity-end mirror which can only compensate the wavefront aberration of the elements in the two-pass beamline.…”

Wavefront Shaping by a Small-Aperture Deformable Mirror in the Front Stage for High-Power Laser Systems

“…Some devices have recently been employed for wavefront correction in high-power laser systems, and include stimulated Brillouin scattering phase conjugation mirrors (SBS-PCMs) [18][19][20][21][22], a liquid-crystal spatial light modulator (SLM) [23], and a deformable mirror (DM) [24][25][26]. Using SBS-PCMs is a passive method for wavefront shaping, and they are used as cavity end mirrors 2 of 9 that can only compensate the wavefront aberration of the elements in a double-pass structure.…”