Effects of temperature gradient on growth of SrB₄O₇ crystals by the micro-pulling-down method

Abstract

  SrB₄O₇ (SBO) shows superior transparency in the vacuum ultraviolet (UV) region, a high radiation damage threshold, and high nonlinearity, and SBO crystals have therefore attracted great interest as materials for low-cost, high-power UV light sources. To use SBO crystals as laser sources, it is essential to grow transparent SBO crystals. Here we show the effects of temperature gradient G on the growth of SBO crystals by the micro-pulling-down method. At low G, SBO crystal fibers were obtained. The density of striations and the size of voids also decreased with decreasing G. These results demonstrate that a low G is essential for growing completely transparent SBO crystal fibers. In addition, we considered the effects of G on the oscillatory growth of SBO crystals in relation to latent heat removal.