Damage growth in fused silica optics at 351 nm: refined modeling of large-beam experiments

Abstract

Up to now, laser damage growth on the exit surface of fused silica optics has been mainly considered as exponential, the growth coefficient depending essentially on fluence. From experiments with large beams carried out at 351 nm under nanosecond pulses, a statistical analysis is conducted leading to a refined representation of the growth. The effect of several parameters has been taken into account to describe precisely the growth phenomenon. The two principal parameters proved to be the mean fluence and the size of the damage sites. Nevertheless, contributions of other parameters have been estimated too: the number of neighbors around the damage site, the shot number, etc. From experimental results, a model smoothed on a statistical approach is developed that permits the description of a complete sequence of growth. To evaluate the relevance of the modeling approach, the occluded area estimated from modeling is compared with the ones experimentally measured. For this purpose, numerical growth methods have been developed too. It is shown that the approach outlined is appropriate for a more precise description of the growth.

Investigations on laser damage growth in fused silica with simultaneous wavelength irradiation

“…The understanding of this phenomenon (referred to as "LID growth") enables the development of mitigation techniques [9,10]. Many studies have been conducted in order to determine how LID sites grow at 1ω [11,12], as well as at 3ω [13][14][15][16], expressing the growth coefficient as a function of the laser fluence. These studies have been performed using large homogeneous beams > 10 mm 2 .…”

Evaluation damage threshold of optical thin-film using an amplified spontaneous emission source

“…The ASE source is delivered from SG-II high power laser system with a certain spectral width and a uniform intensity distribution. According to the standard ISO-11254 of the damage threshold measurement 16,17 , a new damage threshold testing facility using ASE as the irradiation source is built. The damage threshold of the TiO 2 high reflection film is 14.4 J/cm 2 , obviously higher than that of 7.4 J/cm 2 tested by the laser source with pulse duration of 9 ns, leading to an accurate evaluation of the damage threshold.…”

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

“…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 Correspondence to: Z. Lu, Room 311, 2A Building, 2#Yikuang Street, Nangang, Harbin 150080, China. Email: zw lu@sohu.com 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][28][29][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][35][36] .…”

“…Email: zw lu@sohu.com 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][28][29][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][35][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][26][27][28] , high-energy physics experiments [31,32] and many more potential applications [33] .…”