Fabrication of spherical mitigation pit on KH_2PO_4 crystal by micro-milling and modeling of its induced light intensification

Cheng, Jian; Chen, Mingjun; Liao, Wei; Wang, Haijun; Xiao, Yong; Li, Mingquan

doi:10.1364/oe.21.016799

Cited by 32 publications

(19 citation statements)

References 22 publications

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“…Then, incident lasers with pulse fluence increasingly ramped up are adopted until damage is observed. The LIDT is defined as the lowest fluence at which the damage occurs [44]. The laser damage experiment is carried out using a Q-switched Nd: YAG pump lasers (SGR-Exra-10, provided by the Beamtech Company (Beijing, China).…”

Section: Laser Damage Testmentioning

confidence: 99%

Effect of Polishing-Induced Subsurface Impurity Defects on Laser Damage Resistance of Fused Silica Optics and Their Removal with HF Acid Etching

et al. 2017

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Laser-induced damage on fused silica optics remains a major issue that limits the promotion of energy output of large laser systems. Subsurface impurity defects inevitably introduced in the practical polishing process incur strong thermal absorption for incident lasers, seriously lowering the laser-induced damage threshold (LIDT). Here, we simulate the temperature and thermal stress distributions involved in the laser irradiation process to investigate the effect of impurity defects on laser damage resistance. Then, HF-based etchants (HF:NH 4 F) are applied to remove the subsurface impurity defects and the surface quality, impurity contents and laser damage resistance of etched silica surfaces are tested. The results indicate that the presence of impurity defects could induce a dramatic rise of local temperature and thermal stress. The maximum temperature and stress can reach up to 7073 K and 8739 MPa, respectively, far higher than the melting point and compressive strength of fused silica, resulting in serious laser damage. The effect of impurity defects on laser damage resistance is dependent on the species, size and spatial location of the defects, and CeO 2 defects play a dominant role in lowering the LIDT, followed by Fe and Al defects. CeO 2 defects with radius of 0.3 µm, which reside 0.15 µm beneath the surface, are the most dangerous defects for incurring laser damage. By HF acid etching, the negative effect of impurity defects on laser damage resistance could be effectively mitigated. It is validated that with HF acid etching, the number of dangerous CeO 2 defects is decreased by more than half, and the LIDT could be improved to 27.1 J/cm 2 .

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Section: Laser Damage Testmentioning

confidence: 99%

Effect of Polishing-Induced Subsurface Impurity Defects on Laser Damage Resistance of Fused Silica Optics and Their Removal with HF Acid Etching

et al. 2017

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“…light intensity distribution caused by surface crack and contaminant [10][11][12] . The LIEF is defined as maximal light intensity enhancement caused by surface cracks and contaminants in the certain domain.…”

Section: \ F =mentioning

confidence: 99%

Combined modulation to incident laser by subsurface crack and contaminant on fused silica

Wang

Chen

Xiao

et al. 2018

Pacific-Rim Laser Damage 2018: Optical Materials for High-Power Lasers

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Subsurface defects and contaminations will be generated during the grinding and polishing processes of optical components. Combined modulation is one of the important factors for the laser-induced damages of fused silica. In this paper, by using 2D finite-difference time-domain method, the light intensity distribution modulated by both radial crack and contaminant is studied on front/rear surface, respectively. The results show that the light intensity distribution is significantly affected by the aspect ratio of radial crack and the relative position between radial crack and contaminant. The simulations of the combined modulation on rear surface show that larger LIEFs are generated at certain relative positions compared with those in the single modulation of radial crack or contaminant. Meanwhile, with the increase of distance, the LIEFs are wave-like up and down fluctuations, and gradually tend to stable values. When there is no total internal reflection, the LIEF in contaminant on the crack wall rises significantly with increase of distance, the maximum LIEF occurs when the contaminant is near the intersecting line between radial crack and rear surface. The simulation of the combined modulation on front surface show that the variation of LIEFs in global domain are not very prominent.

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“…The light intensification is characterized by light intensity enhancement factor, which is uniform distribution inside a perfect KDP crystal. The amplitude of light field is responsible for non-uniform energy distribution, nonlinear increase of intense laser and consequent decline of laser damage resistance [18,19]. In numerical simulation, a 3ω (λ = 355 nm) laser with an electric field intensity normalized to 1 V/m was assumed to irradiate the front surface of the KDP crystal in normal direction, i.e.…”

Section: Damage Mechanics Of Scratched Kdpmentioning

confidence: 99%

Laser induced damage due to scratches in the surface of nonlinear optical crystals KH2PO4 (KDP)

Zhu

Zhang

et al. 2017

J. Eur. Opt. Soc.-Rapid Publ.

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Fabrication of spherical mitigation pit on KH_2PO_4 crystal by micro-milling and modeling of its induced light intensification

Cited by 32 publications

References 22 publications

Effect of Polishing-Induced Subsurface Impurity Defects on Laser Damage Resistance of Fused Silica Optics and Their Removal with HF Acid Etching

Effect of Polishing-Induced Subsurface Impurity Defects on Laser Damage Resistance of Fused Silica Optics and Their Removal with HF Acid Etching

Combined modulation to incident laser by subsurface crack and contaminant on fused silica

Laser induced damage due to scratches in the surface of nonlinear optical crystals KH2PO4 (KDP)

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