Effect of postgrowth processing technology and laser radiation parameters at wavelengths of 2091 and 1064 nm on the laser-induced damage threshold in ZnGeP 2 single crystal

• Published in: Quantum electronics (Woodbury, N.Y.) N.Y.), 2021-04, Vol.51 (4), p.306-316
• Main Authors: Yudin, N.N., Antipov, O.L., Gribenyukov, A.I., Eranov, I.D., Podzyvalov, S.N., Zinoviev, M.M., Voronin, L.A., Zhuravleva, E.V., Zykova, M.P.
• Format: Article
• Language: English
• ISSN: 1063-7818; 1468-4799
• DOI: 10.1070/QEL17389

We report a study of the effect of postgrowth treatment of ZnGeP 2 single crystals (low-temperature annealing, irradiation with fast electrons, polishing of working surfaces) and the conditions of exposure to repetitively pulsed laser radiation [wavelength (2091 or 1064 nm), pulse repetition rate, beam diameter, exposure time, sample temperature] on the laser-induced damage threshold (LIDT) of the surfaces of these crystals. It is found that thermal annealing of ZnGeP 2 single crystals and their irradiation with a flux of fast electrons, which increase the LIDT at a wavelength of λ = 1064 nm, do not lead to a change in this threshold at λ = 2091 nm. It is shown that ZnGeP 2 elements with lower optical losses in the spectral range 0.7 – 2.5 μm have a higher LIDT at λ = 2091 nm both immediately after fabrication and after postgrowth processing. An increase in the threshold energy density of laser radiation by a factor of 1.5 – 3 at λ = 2091 nm is revealed with a decrease in the crystal temperature from zero to –60 °C. The fact of reversible photodarkening of the propagation channel of laser radiation in ZnGeP 2 in the predamage region of parameters is established by the method of digital holography.