Laser induced damage in coatings for cryogenic Yb:YAG active mirror amplifiers

Journal Article · Fri Aug 07 00:00:00 EDT 2020 · Optics Letters

DOI:https://doi.org/10.1364/OL.399293· OSTI ID:1646528

Wang, Hanchen; Meadows, Alexander R.; Jankowska, Elzbieta; Randel, Emmett; Reagan, Brendan A.; Rocca, Jorge J.; Menoni, Carmen S.

We report results of a study of the laser induced damage threshold (LIDT) behavior of ion beam sputtered ${\mathrm{H}\mathrm{f}\mathrm{O}}_2/{\mathrm{S}\mathrm{i}\mathrm{O}}_2$ multilayer coatings on Yb:YAG using 1-on-1 and N-on-1 test protocols. The tests were conducted at ambient, vacuum, and cryogenic conditions using 280 ps pulses at $\mathrm{\lambda \; <\#comment/>}=1030\mathrm{n}\mathrm{m}$ . The 1-on-1 LIDT of antireflection (AR) stacks is found to be only slightly reduced under vacuum and cryogenic conditions, while that of high reflectivity (HR) stacks is insensitive to environmental conditions within the uncertainty of the measurements. Cryogenic N-on-1 tests show the LIDT of the HR coating is almost the same as in the 1-on-1 tests. Conversely, the cryogenic N-on-1 test of the AR coating shows damage at $\sim \; <\#comment/>13\mathrm{J}/{\mathrm{c}\mathrm{m}}^2$ , a fluence lower than the $20.4\mathrm{J}/{\mathrm{c}\mathrm{m}}^2$ of 1-on-1 tests. The AR damage behavior is found to be affected by imperfections at the Yb:YAG surface. These findings show that high surface quality is required to increase energy extraction from active mirror laser amplifiers.

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0016136
• OSTI ID: 1646528
• Journal Information: Optics Letters, Journal Name: Optics Letters Vol. 45 Journal Issue: 16; ISSN 0146-9592
• Publisher: Optical Society of America
• Country of Publication: United States
• Language: English