Bulk laser-induced damage resistance of SrB4O7 single crystals under 266-nm DUV laser irradiation

The bulk laser-induced damage threshold (LIDT) of a strontium tetraborate (SrB4O7, SBO) single crystal has been measured for the first time. Single-shot and multi-shot tests are carried out using a 266-nm deep ultraviolet (DUV) laser. Under single-shot irradiation, the bulk LIDT of SBO crystal is 1.5 times higher than that of a synthetic silica glass. On the other hand, under multi-shot irradiation, the bulk LIDT of SBO is also higher than synthetic silica glass regardless of the number of shots. When the number of shots increased from 102 to 104, SBO crystal’s bulk LIDT has only decreased by less than 11 % compared to 44 % of synthetic silica glass. Although the damage mechanism of SBO crystal under multi-shot irradiation is considered to be due to material modification fatigue, SBO single crystals are found to be excellent optical materials that exhibit bulk laser-induced damage resistance in the DUV region.