Comparison of Laser-Induced Bulk Modifications in Glass by Femtosecond Pulses Using Single Pulses, MHz- and GHz-Bursts

Transparent laser glass welding is an application that is attracting growing interest. Indeed, it is a chemical-free assembly technology that uses localized heating, while effectively limiting thermal damage. This makes it particularly well-suited for brittle and heat-sensitive glass components, especially in temperature-sensitive technologies. Current researches are focused on optimizing the welding process by exploring different laser regimes and investigating how materials respond under these conditions, such as the MHz-burst mode [1]. An other interesting regime, the GHz-burst mode is becoming more prominent in various glass processing applications in recent years [2], [3]. Its unique capability to gradually heat materials through specific energy deposition mechanisms could enhance the melt pool size, facilitating a more robust and efficient welding process. In this contribution, we present a comparative study of bulk modification morphology in the repetitive single pulse, in the MHz-burst, and in the GHz-burst regimes on sodalime and fused silica. The aim of this study was to establish the process windows, in terms of pulse or burst energy and scanning velocity, for the three regimes to get a better understanding of the process.