Influence of the Characteristics of Multilayer Interference Antireflection Coatings Based on Nb, Si, and Al Oxides on the Laser-Induced Damage Threshold of ZnGeP2 Single Crystal

Abstract

In this work, the effect of the defect structure and the parameters of antireflection interference coatings based on alternating layers of Nb2O5/Al2O3 and Nb2O5/SiO2 layers on the laser-induced damage threshold of ZGP crystals under the action of Ho:YAG laser radiation at a wavelength of 2.097 μm was determined. Coating deposition was carried out using the ion-beam sputtering method. The laser-induced damage threshold of the sample with a coating based on alternating layers Nb2O5 and SiO2 was W0d = 1.8 J/cm2. The laser-induced damage threshold of the coated sample based on alternating layers of Nb2O5 and Al2O3 was W0d = 2.35 J/cm2. It has been found that the presence of silicon conglomerates in an interference antireflection coating leads to a decrease in the laser-induced damage threshold of a nonlinear crystal due to local mechanical stresses and the scattering of incident laser radiation.

Titanium and silicon oxides for infrared AR coating design

“…Oxide films have better mechanical characteristics, resistance to scratching and abrasion. In our previous works, we used such oxide materials as Nb2O5 and SiO2, from which we constructed an optical antireflection coating [7] on a ZGP substrate. However, it had a low LIDT value.…”

The Influence of Angstrom-Scale Roughness on the Laser-Induced Damage Threshold of Single-Crystal ZnGeP2

“…In this regard, the potential for the practical use of the OPO data of the mid-IR range is associated with the need to improve the methods for the processing of the working surfaces of crystals to increase their LIDT. The problem of ZGP optical breakdown by laser radiation at wavelengths from 1.064 µm to 10 µm is the subject of several published articles [11][12][13][14][15][16][17][18]. These articles revealed a significant difference in the magnitude of the LIDT of the ZGP crystal at the wavelengths of 1.064 µm and 2.1 µm [11].…”