Effect on scattering of complex morphology of DKDP bulk damage sites

Carr, C. W.; Feit, Michael D.; Muyco, Julie; Rubenchik, Alexander M.

doi:10.1117/12.585927

Cited by 11 publications

(9 citation statements)

References 7 publications

(4 reference statements)

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“…More details on sample preparation can be found in Ref. 23. The Raman spectrum of DKDP shows the typical double-peak signature, at 887 and 963 cm −1 , derived from the KDP Raman mode at 911 cm −1 upon deuteration.…”

Section: Resultsmentioning

confidence: 99%

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Stoichiometric changes to KH 2 PO 4 during laser-induced breakdown

et al. 2005

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The local structure of KH 2 PO 4 crystals (so-called KDP) at laser-induced damage sites created by irradiation with ∼ 3-ns, 355-nm laser pulses is studied by a combination of Raman scattering and photoluminescence spectroscopies. We compare spectra from pristine material, surface and bulk laser-induced damage sites, as well as from KPO 3 references. Results show that irradiation with fluences above the laser-induced breakdown threshold leads to stoichiometric changes at surface damage sites but not at bulk damage sites. New spectroscopic features are attributed to dehydration products. For the laser irradiation conditions used in this study, the decomposed near-surface layer absorbs photons at ∼ 3.4 eV (364 nm). These results may help explain the recently reported observation that surface laser damage sites in KDP crystals tend to grow with subsequent exposure to high-power laser pulses, while bulk damage sites do not.

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Section: Resultsmentioning

confidence: 99%

“…Preliminary results 23 have been obtained in micro-Raman measurements from "exposed" bulk damage sites in DKDP crystals. In order to gain access to bulk LID sites, samples were prepared by "cleaving" a DKDP sample containing bulk damage, previously created by exposure to ∼ 3-ns, 355-nm laser pulses.…”

Section: Resultsmentioning

confidence: 99%

Stoichiometric changes to KH 2 PO 4 during laser-induced breakdown

et al. 2005

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“…When we repeated these measurements using white light scattering as our illumination source we observed the same general trend but found the pinpoints to be substantially smaller than reported previously (see figure 1). We have shown previously that the discrepancy in these two observations can be attributed to the illumination sources used 8 . Coherent light sources will make some, but not all, pinpoints appear larger.…”

Section: Introductionmentioning

confidence: 81%

A summary of recent damage-initiation experiments on KDP crystals

et al. 2005

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We summarize recent investigations of the density and morphology of bulk damage in KDP crystals as a function of pulse duration, temporal profile, wavelength, and energy fluence. As previously reported by Runkel et al. 1, we also find that the size of bulk damage sites varies roughly linearly with pulse duration for pulses between 1 ns and 9 ns. However this trend no longer applies at pulse durations below 1 ns. Experiments measuring the damage density and size distribution as a function of wavelength confirm many previous works which indicated a strong dependence of damage density with wavelength. However, we also find that the size of damage sites is relatively insensitive to wavelength. Further we see damage due to Flat-In-Time (FIT) pulses has different pulse length and fluence dependence than Gaussian pulses. We demonstrate that a simple thermal diffusion model can account for observed differences in damage densities due to square and Gaussian temporally shaped pulses of equal fluence. Moreover, we show that the key laser parameter governing size of the bulk damage sites is the length of time the pulse remains above a specific intensity. The different dependences of damage density and damage site size on laser parameters suggest different absorption mechanisms early and late in the damaging pulse.

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“…The limitation arises because KDP tends to damage at fluences lower than other typical optical materials used in such systems. 6,7,8 Damage in KDP is primarily manifested as discrete localized microcavities in the bulk of the crystal.…”

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confidence: 99%

“…11,12 While the actual amount of energy lost due to scattered light is small, pinpoints in large numbers can create intensity fluctuations from their collective scatter (contrast) which enhances the likelihood of damaging components downstream in a laser system. 6,7,13 For pinpoints induced by 351-nm (3ω) light, size and density have been shown to depend on laser parameters such as pulse length, pulse duration, pulse shape, and fluence. 4,9,10,14,15 Both pinpoint size and density have been shown to vary with pulse duration for a fixed fluence.…”

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confidence: 99%