Kyropoulos growth of a 300 g SrB 4 O 7 single crystal using a twin-type stirring blade

Abstract We report the successful Kyropoulos growth of a large strontium tetraborate (SrB 4 O 7 , SBO) single crystal that weighs more than 300 g. In order to grow the large and transparent crystal, a new twin-type stirring blade was used along with a 150 mm diameter crucible. The use of the stirring blade results in the production of the world’s largest SBO crystal with dimensions of 100 mm ( a ) ×30 mm ( b ) ×32 mm ( c ), a weight of 328.2 g, and wide transparency down to 130 nm. These results will then lead to the development of large SBO crystals as optical window materials for high-power DUV laser processing systems.