Bonding of optical materials by femtosecond laser welding for aerospace and high power laser applications

A process for joining optical materials by direct bonding reinforced by femtosecond laser welding is presented. It is suitable for assembly of components for aerospace and high power laser applications where adhesives must be avoided. Joining is realized in two steps. Firstly, materials are direct bonded so as to achieve a state of optical contact preferably over the whole area between bonded surfaces. The second step consists in sealing the direct bonded region by writing weld lines by femtosecond laser pulses at the outskirts of the bonding surface. The bond, applicable to both similar and dissimilar material combinations, is resistant to important mechanical and thermal constraints and does not alter the assembly's optical transmission properties inside the sealed area. Most importantly, the drawbacks of common joining methods are avoided, such as premature aging, degassing, photo-bleaching and limited applicable material combinations.