quality assessment of variable reflectivity laser mirrors with high laser –induced damage threshold and structural analysis

We report the results of an experimental study on the fabrication of a multilayer variable reflectivity laser mirror and the morphological analysis of optical thin film layers. in a design procedure, a series of variable reflectivity laser mirrors are fabricated and characterized with different methods. in this research, based on pulsed solid-state nd:yag lasers at 1064 nm, two types of variable reflectivity laser mirrors with (hfo2/sio2) and (zro2/sio2) materials are fabricated by electron beam evaporation method. the central reflectivity of r0 =30 and 35 % for two super gaussian orders of n=3 and 4 is manufactured and qualified by ellipsometry and laser beam scan methods. the laser-induced damage threshold experiments demonstrated that, the vrms with multilayers of hfo2/sio2, have a higher laser-induced damage threshold than zro2/sio2, which was 10 j/cm2 and 7 j/cm2, correspondingly. also, in a novel and exact fesem approach, the morphological structure of the vrm thin layers was monitored which gives a deeper insight into the layer structure and helped us to calibrate the pvd device for shaped vrm.