High-power Nd³⁺:glass laser system in KAIST (Sinmyung I)

Abstract

A high-power Nd3+:glass laser system has been constructed and tested. This system consists of a master oscillator, a four-pass amplifier for preamplification, and five-stage amplifiers. The system has been demonstrated in excess of 80 J (2 TW) at 40-ps pulse duration. Final laser beam quality was quite good due to the compensation of the polarization distortion in the four-pass preamplifier, the minimization of the diffraction effect by the image relaying, and the elimination of high spatial frequency components by the spatial filtering. This enables us to obtain high laser output power without any severe spatial spiking effects. Gains and spatial profiles of output pulses were measured after each amplifier stage.

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 past few decades, a series of medium-scale laser systems were established worldwide in many famous labs, such as the Optical Sciences Laser (OSL) in Lawrence Livermore National Lab (LLNL) [23] , the ALISE facility in CEA-CESTA, France [24] , the HERCULES facility in University of Michigan, United States [25] , the J-KAREN system in Japan Atomic Energy Agency [26] , the Nd:glass laser with the pulse energy of several hundred Joules in the Institute of Applied Physics of the Russian Academy of Sciences [27–30] , the HELEN system at the Atomic Weapons Establishment (AWE), UK [31] , the two-arm Nd:glass laser system in Raja Ramanna Centre for Advanced Technology (RRCAT), India [32] , the Sinmyung I system in the Korea Advanced Institute of Science and Technology [33] and the HiLASE system in development at the Institute of Physics ASCR, Czech Republic [34–36] . These lasers are used for many emerging applications such as shock hardening of materials, laser-induced damage threshold testing [23, 24] , pumping of Ti:Sa lasers [25–28] , high-energy physics experiments [31, 32] and many more potential applications [33] .…”