Low thermal stress and high-strength interface in brazing welding Nd:YAG-based advanced laser components

Abstract

Cu/Nd:YAG joints present a critical challenge for packaging advanced Nd:YAG-based laser components. Owing to the significant mismatch in the thermal expansion coefficients and the poor metallurgical compatibility between the ceramic and metal, the resulting high thermal stress and serious void defects deteriorate beam quality and structural lifetime. In this work, Cu and Nd:YAG were subjected to braze welding at a lower temperature of 190 °C, with reduced thermal stress and sound. It was obtained by designing a Ti–Pt–Au film as the transition layer and employing a vacuum-deposited indium film as the welding layer. Based on this approach, herein, practical sandwiched Cu/Nd:YAG/Cu laser components were fabricated for space-grade applications. Under extreme service conditions of satellite-borne laser systems, including large diurnal temperature variations and complex cyclic loads, the tested beam morphology and simulated thermal stress of the prepared laser component during operation satisfied the application requirements. These findings not only provide an efficient packaging solution for Nd:YAG-based laser components but also enrich the theoretical foundation for achieving low thermal stress and high-strength interface in ceramic/metal dissimilar joints.