Improvements in the laser damage behavior of Ta2O5/SiO2interference coatings by modification of the top layer design

Patel, D.; Schiltz, Drew; Langton, P. F.; Emmert, Luke A.; Acquaroli, Leandro N.; Baumgarten, Cory; Reagan, Brendan; Rocca, J. J.; Rudolph, W.; Markosyan, A. S.; Route, R. R.; Fejer, M. M.; Menoni, Carmen S.

doi:10.1117/12.2030380

Cited by 8 publications

(6 citation statements)

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“…However, reflection bandwidth, dispersion and damage threshold are interdependent, restricting each other [8]. Thereby, the LIDT of broad-bandwidth, low-dispersion mirrors have become a recognized research focus [8][9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Effect of Electric Field Regulation on Laser Damage of Composite Low-Dispersion Mirrors

Zhang

Wang

et al. 2021

Coatings

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Low dispersion mirrors are important because of their potential use in petawatt (PW) laser systems. The following two methods are known to increase the laser-induced damage threshold of low dispersion optical components: use of a wide-bandgap-material protective layer and control of electric field distribution. By controlling the electric field distribution of composite low-dispersion mirrors (CLDM), we shift the electric field peaks from the material interface into the wide-bandgap material. However, the damage threshold of modified-electric-field composite low dispersion mirror (E-CLDM) does not increase. Damage morphology shows that the initial damaged layer is Ta2O5. An immediate cause is the enhancement of the electric field in internal layers caused by surface electric field regulation. Theoretical calculations show that the damage threshold of CLDM or E-CLDM is determined by the competition results of bandgap and the electric field of layer materials. The CLDM with different materials or different protective layer periods can be optimally designed according to the electric field competition effect in the future.

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Section: Introductionmentioning

confidence: 99%

Effect of Electric Field Regulation on Laser Damage of Composite Low-Dispersion Mirrors

Zhang

Wang

et al. 2021

Coatings

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“…This approach, also extended to a higher number of layers (also called reduced standing wave design), was proved to improve the LIDT in the short pulse regime [13,[23][24][25]. Ternary mirror designs were also proposed with the idea of using HfO2 only where high electric field intensities could not be avoided, and a higher index material (albeit less damage resistant) elsewhere to reduce the number of pairs necessary to attain the desired reflectivity [26]. Interestingly enough, authors studied the role of interface on stress [27].…”

Section: Introductionmentioning

confidence: 99%

Robust optimization of the laser induced damage threshold of dielectric mirrors for high power lasers

Chorel¹,

Lanternier²,

Lavastre³

et al. 2018

Opt. Express

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We report on a numerical optimization of the laser induced damage threshold of multi-dielectric high reflection mirrors in the sub-picosecond regime. We highlight the interplay between the electric field distribution, refractive index and intrinsic laser induced damage threshold of the materials on the overall laser induced damage threshold (LIDT) of the multilayer. We describe an optimization method of the multilayer that minimizes the field enhancement in high refractive index materials while preserving a near perfect reflectivity. This method yields a significant improvement of the damage resistance since a maximum increase of 40% can be achieved on the overall LIDT of the multilayer.

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“…We have already demonstrated increases in the laser damage threshold fluence of a Ta 2 O 5 /SiO 2 high reflection multilayer through replacement of Ta 2 O 5 with HfO 2 in the top three bilayers when tested using 0.35 ns pulses at λ = 1 μm [3]. We have also demonstrated the role of SiO 2 capping layers that reduce the electric field intensity in the structure to improve the laser induced damage resistance from laser pulses of 0.19 ns and 4 ns duration [4].…”

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confidence: 95%

“…The coatings were deposited by ion beam sputtering (IBS) using a metal target for the reactive sputtering of Ta 2 O 5 and a dielectric target for the deposition of SiO 2 . Further information on the deposition process has been presented elsewhere [3]. The interference coatings were deposited on one inch diameter, 0.25 inch thick fused silica substrates with an RMS roughness of 0.6 nm.…”

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confidence: 99%

Laser Damage Resistant Ta2O5/HfO2/SiO2 Multilayer Mirrors by Ion Beam Sputtering

Schiltz

Patel

Emmert

et al. 2015

Advanced Photonics 2015

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We show the threshold fluence for damage of Ta 2 O 5 /SiO 2 multilayer interference coatings measured using 0.19 ns and 4 ns pulses with λ=1.03 µm can be increased by 2x when modifying the coating's top layer design. OCIS codes: (310.1620) Interference coatings; (310.4165) Multilayer design; (310.1860) (350.1820) Damage.Ta 2 O 5 is a prime candidate for a high index material in interference coatings given its low intrinsic stress [1], superior layer smoothness and uniformity [2], and low absorption and scattering losses. Its laser damage resistance at nanosecond pulse durations is, however, lower than similar multilayers that employ HfO 2 or Y 2 O 3 as the high index materialWe have already demonstrated increases in the laser damage threshold fluence of a Ta 2 O 5 /SiO 2 high reflection multilayer through replacement of Ta 2 O 5 with HfO 2 in the top three bilayers when tested using 0.35 ns pulses at λ = 1 μm [3]. We have also demonstrated the role of SiO 2 capping layers that reduce the electric field intensity in the structure to improve the laser induced damage resistance from laser pulses of 0.19 ns and 4 ns duration [4]. In this work, the effect of combining design techniques to increase the damage resistance of Ta 2 O 5 /SiO 2 high reflectors is explored and compared with HfO 2 /SiO 2 and Ta 2 O 5 /SiO 2 quarter-wave designs.Interference coatings based on Ta 2 O 5 /SiO 2 were designed for normal incidence and 99.9% reflectivity at λ = 1μm. The coatings were deposited by ion beam sputtering (IBS) using a metal target for the reactive sputtering of Ta 2 O 5 and a dielectric target for the deposition of SiO 2 . Further information on the deposition process has been presented elsewhere [3]. The interference coatings were deposited on one inch diameter, 0.25 inch thick fused silica substrates with an RMS roughness of 0.6 nm. No post annealing or ion assisting during growth was performed.A quarter-wave stack consisting of 15 pairs of Ta 2 O 5 /SiO 2 layers, (Ta 2 O 5 / SiO 2 ) 15 , was modified to increase laser damage resistance. Each design involves adding an extra λ/4 layer of SiO 2 to the top of the coating, which reduces the overall E-field due to enhanced constructive interference from reflections off the top air-coating interface and successive interfaces. In addition, one of these designs incorporates HfO 2 by replacing Ta 2 O 5 top layers. A final modified design incorporates both of these techniques while reducing the thickness of the top four HfO 2 quarter wave layers to shift the peak of the electric field into thicker SiO 2 layers as proposed by Apfel et al [5].The 100-on-1 laser damage testing was performed using pulses from a Yb:YAG chirped pulse amplification laser system with a 1/e 2 focal spot size of 90 μm [6]. 300 fs pulses from a Yb:KYW oscillator are stretched to .19 ns and sent through a 100 Hz rep rate Yb:YAG regenerative amplifier. Further amplification to tens of millijoules is performed in a cryogenically cooled "thick disk" Yb:YAG amplifier operating in an active mirror configuration. ...

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Improvements in the laser damage behavior of Ta₂O₅/SiO₂interference coatings by modification of the top layer design

Cited by 8 publications

References 0 publications

Effect of Electric Field Regulation on Laser Damage of Composite Low-Dispersion Mirrors

Effect of Electric Field Regulation on Laser Damage of Composite Low-Dispersion Mirrors

Robust optimization of the laser induced damage threshold of dielectric mirrors for high power lasers

Laser Damage Resistant Ta2O5/HfO2/SiO2 Multilayer Mirrors by Ion Beam Sputtering

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