Investigation on practical use of disordered type new laser crystals

研究了大直径、高质量的钙铌镓石榴石(CNGG)单晶的生长条件及其激光性能，为实际大批量生产和新型光电系统的建立提供了理论依据。确定了激光激活剂Nd3+、Tm3+和Er等激活剂在CNGG单晶中的平衡分配系数，以控制晶体的均匀性。还测定了CNGG单晶的精确同成分熔体组成。证实了高掺杂和高质量晶体生长的可能性。由于CNGG单晶的熔化温度为1470ﾟC，因此可以用铂坩埚进行晶体生长。基于无序型结构的掺杂CNGG单晶的宽吸收光谱和荧光光谱显示出良好的性能，可以作为激光二极管(LD)泵浦的新型固体激光器的基质，特别是一维LD阵列泵浦。利用一维激光二极管列阵泵浦的激光输出功率超过了单晶的激光输出功率，并开发了连续加料系统，实现了对晶体成分的精确控制，以及实现了芯掺杂和多功能结构的新的晶体生长方法，以适应实际的大规模生产。研究了坩埚及其周围结构的复杂结构和精确的生长条件，讨论了大尺寸晶体生长过程中出现扭曲现象的机理和原因。为了避免这些现象，研究了炉内的生长条件和温度场。

Growth conditions of calcium niobium gallium garnet (CNGG) single crystals with large diameter and high quality, and those laser properties were investigated for the practical mass production and the creation of new opto-electronic system.The equilibrium distribution coefficients of lasing activators such as Nd^<3+>, Tm^<3+> and Er^<3+> in CNGG single crystals, were determined to control the uniformity of crystals, and were larger than those of other garnet crystals. The precise congruent melt composition of the CNGG single crystal was also determined. The possibility of high doping and the growth of high quality crystals were confirmed. Since the melting temperature of the CNGG single crystal was 1470ﾟC,Pt crucibles were found to be available for the crystal growth. Usefulness of Pt crucibles compared with Ir ones based on the high degree of varying the growth atmosphere and reducing the cost, was confirmed.Broad absorption and fluorescence spectra of doped CNGG single crystals based on the disordered type structure showed profitable properties as the new solid state laser host pumped by a laser diode (LD), especially by one dimensional LD array. The output laser power pumped by one dimensional LD array of Nd : CNGG single crystals exceeded that of Nd : YAG.Continuous charging system which enables the precise control of the grown crystal composition, and new crystal growth method which enables core doping and multi-functional structure, were also developed for the practical mass production. Complex structures of crucibles and surrounding constructions, and precise growth conditions were investigated.Mechanism and origin of twisting phenomena which appeared during the growth of large size crystals were discussed. The growth conditions and temperature fields of inside furnaces to avoid these phenomena were investigated.