Objective Er-Yb glass is a critical component in 1535 nm eye-safe laser systems. When such a laser enters the human eye, it is strongly absorbed by water molecules present in the cornea and lens. The eye-safe irradiation threshold of this laser is 10⁶ times higher than that of Nd:YAG lasers, highlighting its significant potential in laser medicine, lidar, and military applications. However, Er-Yb glass exhibits several inherent limitations, including high hydrophilicity, a large thermal expansion coefficient, low hardness, and a low glass transition temperature. These properties often lead to substantial thermal stress and poor film adhesion during coating processes. Furthermore, excessive residual stress within the coating during laser operation can result in laser-induced ablation. Therefore, it is essential to develop low-stress thin films with superior adhesion on Er-Yb glass substrates to meet the reliability requirements of practical eye-safe laser systems.

Methods This paper employs COMSOL Multiphysics software to develop a thermal-stress simulation model of the coating. By introducing a SiO₂ bonding layer to alleviate thermal stresses in the coating, the challenge of coating delamination is effectively addressed. By designing of gradient process parameters, a mathematical model that correlates residual stress to ion source energy and coating thickness is established. Optimal process parameters are screened to prepare low-stress antireflective coatings.

Results and Discussions After introducing a SiO₂ bonding layer, COMSOL Multiphysics showed that the thermal stress within the multilayer film was reduced from 417 MPa to 388 MPa (Fig.3), corresponding to a reduction of 29 MPa. Specifically, the thermal stress in the first layer of the multilayer film was reduced from 417 MPa to 127 MPa (Fig.4). Furthermore, adhesion tests confirmed the absence of coating delamination (Fig.5). Through systematic tuning of the ion source parameters for the Ta₂O₅ layer and the thickness-related process parameters for the SiO₂ layer, a mathematical model was developed to achieve stress matching. This enabled the preparation of a low-stress antireflective coating exhibiting a residual stress of −8.61 MPa (Tab.11) and a reflectance of 0.069% (Fig.10).

Conclusions The paper adopts electron beam thermal evaporation ion-assisted deposition (IAD) technology, with Ta₂O₅ and SiO₂ as coating materials, for the design and fabrication of near-infrared antireflective coatings on Er-Yb glass substrates that meet adhesion requirements and possess low-stress characteristics. COMSOL Multiphysics software was employed to develop a thermal-stress simulation model. It was revealed that with SiO₂ serving as the bonding layer, the thermal stress in the first film layer was reduced from 417 MPa to 127 MPa, thereby effectively addressing the problem of film delamination. Through the establishment of a mathematical model correlating residual stress with ion source energy and film thickness, the deposition process was optimized, enabling the preparation of a low-stress film with a residual stress of −8.61 MPa. The resulting film successfully passed adhesion, water boiling, and damp heat tests, exhibiting an average reflectance of 0.069% within the wavelength range of （1535±3） nm, which satisfies the operational requirements of Er-Yb lasers. To further reduce the film stress, future research will concentrate on investigating the influence of interfacial stress on the residual film stress.