BORATE BIREFRINGENT CRYSTAL APPLICABLE TO ULTRAVIOLET (UV) OR DEEP ULTRAVIOLET (DUV) RANGE, AND GROWTH METHOD AND USE THEREOF

摘要

The present invention relates to a borate birefringent crystal applicable to ultraviolet (UV) or deep ultraviolet (DUV) range, with chemical formula of Ba₂Mg(B₃O₆)₂. The borate birefringent crystal belongs to a trigonal system, with space group of R-3 wherein a=0.70528(3) nm, c=1.65520(9) nm and Z=12. The barium magnesium borate birefringent crystal is negative uniaxial (n_en_o) with a birefringence of 0.077-0.229 and a transmission range of 177-3000 nm. The crystal is easy to cut, grind, polish, and preserve, and is stable in air and is not easy to deliquesce. The barium magnesium borate birefringent crystal can be grown by the Czochralski method, flux method or the method of spontaneous crystallization from a melt, and has larger birefringence (n_o−n_e=0.077-0.229). The crystal has important applications in the fields of optics and communications, e.g. for fabricating the polarizing beam splitter prism.