Multispectral Anti-Reflection Coatings Based on YbF3/ZnS Materials on ZnGeP2 Substrate by the IBS Method for Mid-IR Laser Applications

Abstract

A multispectral anti-reflective coating of high radiation strength for laser applications in the IR spectrum for nonlinear ZnGeP2 crystals has been developed for the first time. The coating was constructed using YbF3/ZnS. The developed coating was obtained by a novel approach using ion-beam deposition of these materials on a ZnGeP2 substrate. It has a high LIDT of more than 2 J/cm2. Optimal layer deposition regimes were found for high film density and low absorption, and good adhesion of the coating to the substrate was achieved. At the same time, there was no dissociation of the double compound under high-energy ions.

Physical and Technological Aspects of Laser-Induced Damage of ZGP Single Crystals under Periodically Pulsed Laser Irradiation at 2.1 μm

“…However, the prolonged operation of powerful OPOs and OPGs/OPAs based on ZGP is limited by the laser-induced damage (LID) of this material. In accordance with the results of numerous studies [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], the ZGP LID always occurs at the sample surface or in the sub-surface layer rather than in the bulk in samples subjected to repetitively pulsed nanosecond-pulse-width infrared radiation. A combination of factors associated with defects in the crystal structure in the sub-surface layer and the quality of polishing of the surface itself affects the LID.…”

High-Strength Optical Coatings for Single-Crystal ZnGeP2 by the IBS Method Using Selenide and Oxide Materials

“…As can be seen from Table 1, the rate of deposition of the Al 2 O 3 layer is about 0.1 nm/s, which is approximately 5 times higher than the rate of deposition of the YbF 3 layer (equal to 0.02 nm/s [18]) when targets were sputtered by the IBS method. The sputtering rate of the high-refractive ZnSe material was ~0.09 nm/s, twice as high as ZnS, the sputtering rate of which is 0.04-0.045 nm/s [18]. Thus, the time of sputtering process can be significantly reduced using Al 2 O 3 instead of YbF 3 , where possible, and ZnSe instead of ZnS.…”

“…[14,15]. The approaches described in [17,18] also make it possible to sputter sulfide and fluoride ceramic targets using the IBS method. In previous work [18], the possibility of applying an optical anti-reflection coating with a high LIDT value on a ZnGeP 2 (hereinafter ZGP) substrate was presented.…”

“…The approaches described in [17,18] also make it possible to sputter sulfide and fluoride ceramic targets using the IBS method. In previous work [18], the possibility of applying an optical anti-reflection coating with a high LIDT value on a ZnGeP 2 (hereinafter ZGP) substrate was presented. However, it has been shown that the specific sputtering rate of ZnS and YbF 3 by the IBS method is low [18]; as a result, the sputtering process requires a long time, which causes a negative effect where pollutants and residual gas, in the volume of the sputter chamber, get into the anti-reflective coating, which can significantly affect LIDT.…”

“…In previous work [18], the possibility of applying an optical anti-reflection coating with a high LIDT value on a ZnGeP 2 (hereinafter ZGP) substrate was presented. However, it has been shown that the specific sputtering rate of ZnS and YbF 3 by the IBS method is low [18]; as a result, the sputtering process requires a long time, which causes a negative effect where pollutants and residual gas, in the volume of the sputter chamber, get into the anti-reflective coating, which can significantly affect LIDT. At the same time, in the operating range of the laser system, up to 5 µm, it is possible to use the low-refractive oxide material Al 2 O 3 with ZnS, as shown in [19].…”