LiCAF crystal as a new vacuum ultraviolet optical material with transmission down to 112 nm

Summary form only given. Recently, various new fluoride crystals have been developed as the host crystals for new solid-state tunable ultraviolet and infrared laser materials. Among them, LiCaAlF/sub 6/ (LiCAF) and LiSrAlF/sub 6/ (LiSAF) are the successful material for chromium or cerium doping. For cerium doping in particular, Ce:LiCAF and Ce:LiSAF are attractive solid-stale lasers with their practical tuning region from 288 to 315 nm. In spite of similar tunability and laser efficiency, Ce:LiCAF is even more attractive because of its reduced solarization effects compared with Ce:LiSAF. However, the reason for this difference has not been studied well, and to further improve laser performance, spectroscopic studies of these materials is necessary, including accurate band-gap measurement. In addition, optical material for the ultraviolet and vacuum ultraviolet region has become much more important for the deep ultraviolet lithographic technology required for the semiconductor processing technology of the next century and vacuum ultraviolet spectroscopy using synchrotron orbital radiation. We report that superior transmission characteristics of LiCaAlF/sub 6/ (LiCAF), down to 112 nm, were found for the first time. From the transparent wavelength shorter than that of conventional LiF, the non hydroscopic nature of LiCAF, and the better mechanical properties compared with LiF, LiCAF is shown to be an ideal optical material for the vacuum ultraviolet region.