Multilayer deformation planarization by substrate pit suturing

In the pursuit of 1064 nm high-power laser resistance dielectric coatings in the nanosecond region, a group of HfO₂/SiO₂ high reflectors with and without suture layers were prepared on prearranged fused silica substrates with femtosecond laser pits. Surface morphology, global coating stress, and high-resolution cross sections were characterized to determine the effects of substrate pit suturing. Laser-induced damage resistance was investigated for samples with and without suture layers. Our results indicate considerable stability in terms of the nanosecond 1064 nm laser-induced damage threshold for samples having a suture layer, due to decreased electronic field (e-field) deformation with simultaneous elimination of internal cracks. In addition, a suture layer formed by plasma ion-assisted deposition could effectively improve global mechanical stress of the coatings. By effectively reducing the multilayer deformation using a suture layer, electron-beam high-reflective coatings, whose laser-induced damage resistance was not influenced by the substrate pit, can be prepared.