Ultraviolet-induced transient absorption in potassium dihydrogen phosphate and its influence on frequency conversion

Marshall, C. D.; Payne, Stephen A.; Henesian, Mark A.; Speth, Joel A.; Powell, H. T.

doi:10.1364/josab.11.000774

Cited by 78 publications

(41 citation statements)

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“…It was found that typical damage pinpoints were caused by defects, which efficiently absorbed laser energy, leading to a temperature rise and subsequent 'micro-explosion' [5][6][7] . Various types of bulk defect, such as metallic impurities [8][9][10] , electronic defects [11][12][13] , organic materials, bacteria [14,15] , dislocation [16] and insoluble impurities, have been reported. In 1999, the continuous filtration Correspondence to: Y. Zhao, No.…”

Section: Introductionmentioning

confidence: 99%

Performance of rapid-grown KDP crystals with continuous filtration

Wang

Chang

et al. 2015

High Pow Laser Sci Eng

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Rapid growth processing of KDP crystals was improved by employing continuous filtration to eliminate bulk defects. The performances of the KDP crystals, including scattering defects, laser damage resistance and transmittance, were measured and analyzed. Compared with rapid-grown KDP without continuous filtration, the transmittance in the nearinfrared was increased by at least 2%, almost all of 'micron size' defects were eliminated and 'sub-micron size' defects were decreased by approximately 90%. Laser damage testing revealed that the laser-induced damage thresholds (LIDTs), as well as the consistency of the LIDTs from sample to sample, were improved greatly. Moreover, it identified that 'micron size' defects were the precursors which initiated laser damage at relative lower laser fluence (4-6 J cm −2 ), and there was a lower correlation between smaller size scattering defects and laser damage initiation. The improved consistency in the LIDTs, attributed to elimination of 'micron size' defects, and LIDT enhancement originated from the decreased absorption of the KDP crystals.

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Section: Introductionmentioning

confidence: 99%

Performance of rapid-grown KDP crystals with continuous filtration

Wang

Chang

et al. 2015

High Pow Laser Sci Eng

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“…[15][16][17][18] The laser-induced optical absorption, which limits the device performance, has been attributed to point defects created during crystal growth or produced by radiation during use. [15][16][17][18][19][20][21][22][23][24][25][26][27] Davis et al suggested 15 that proton transport ͑the radiation-induced displacement of a proton from its normal site͒ is a major component of the mechanism responsible for the transient optical absorption. The proposed mechanism for the formation of the absorbing defect centers proceeds as follows: Two-photon absorption of highintensity laser radiation generates electron-hole pairs, a portion of which may eventually evolve into electronic defect states that often lie within the band gap.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure calculations of intrinsic and extrinsic hydrogen point defects inKH2PO4

et al. 2003

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We report first-principles total-energy density-functional theory electronic structure calculations for the neutral and charge states of H intrinsic ͑Frenkel pair͒ and extrinsic ͑H vacancy or interstitial͒ point defects in KH 2 PO 4 . The relaxed atomic structures, the formation energy, the ionization energy, and electron and hole affinities for the various defects have been calculated. For the Frenkel pair, the additional hole leads to a decrease of the OuO bond length between the two O atoms next to the H vacancy, while the effect of the additional electron is small. For the H vacancy, the added hole is trapped and shared by the two O atoms adjacent to the vacancy, reducing dramatically the OuO bond length, thus forming a molecular-type polaron. We find that the positively charged H vacancy introduces states in the gap, in contrast with its neutral state, confirming the experimental suggestion that it is a relevant absorbing center. The negatively charged H vacancy leads to an increase of the two O atoms close to the H vacancy, and does not induce states in the gap. The H interstitial does not interact with the host atoms in the neutral state. However, the addition of an electron leads to the ejection of a H host atom and the subsequent formation of a H 2 interstitial molecule and a H vacancy, in agreement with experimental suggestions. In the positively charged state the H interstitial binds to its nearest-neighbor O atom forming a hydroxyl bond. The H interstitial in both positive and negative charge states induces no defect states in the band gap, in contrast with its neutral state. The calculations provide insights into the role of the charged and neutral defects on the transient optical absorption under irradiation by high-intensity laser beam.

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“…7(a)-7(c) respectively, for a UV beam waist radius of wUV~15 × 104 µm. We used a simple theoretical model by considering a Gaussian temporal profile for the UV pulses in the presence of linear absorption, and assuming the formation of dynamic colorcenters due to two-photon absorption in BBO, to model the defect densities, while also considering the bleaching of the color centers over the entire pulse duration to be negligible [16]. The equations governing the color center densities and the UV intensity through the BBO crystal are given by, 2 4 ( , ) ( , ) 8…”

Section: Two-photon Absorption At 266 Nm In Bbomentioning

confidence: 99%

High-power, high-repetition-rate performance characteristics of β-BaB_2O_4 for single-pass picosecond ultraviolet generation at 266 nm

Kumar¹,

Casals²,

Wei³

et al. 2015

Opt. Express

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Abstract:We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB 2 O 4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such as thermal effects have been studied and confirmed by performing relevant measurements. Angular and temperature acceptance bandwidths in BBO for FHG to 266 nm are experimentally determined, indicating that the effective interaction length is limited by spatial walk-off and thermal gradients under high-power operation. The origin of dynamic color center formation due to two-photon absorption in BBO is investigated by measurements of intensity-dependent transmission at 266 nm. Using a suitable theoretical model, two-photon absorption coefficients as well as the color center densities have been estimated at different temperatures. The measurements show that the two-photon absorption coefficient in BBO at 266 nm is ~3.5 times lower at 200°C compared to that at room temperature. The long-term power stability as well as beam pointing stability is analyzed at different output power levels and focusing conditions. Using cylindrical optics, we have circularized the generated elliptic UV beam to a circularity of >90%. To our knowledge, this is the first time such high average powers and temperature-dependent two-photon absorption measurements at 266 nm are reported at repetition rates as high as ~80 MHz. Bradler and E. Riedle, "Sub-20 fs μJ-energy pulses tunable down to the near-UV from a 1 MHz Yb-fiber laser system," Opt.

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Ultraviolet-induced transient absorption in potassium dihydrogen phosphate and its influence on frequency conversion

Cited by 78 publications

References 1 publication

Performance of rapid-grown KDP crystals with continuous filtration

Performance of rapid-grown KDP crystals with continuous filtration

Electronic structure calculations of intrinsic and extrinsic hydrogen point defects inKH2PO4

High-power, high-repetition-rate performance characteristics of β-BaB_2O_4 for single-pass picosecond ultraviolet generation at 266 nm

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