DEVELOPMENT OF LIGHT WAVEGUIDE OF FLUORIDE GLASS THIN FILMS BY COMBINED SOL-GEL AND FLUORINATION

由于稀土氟化物玻璃在光传输、光纤激光器、光频上转换、光放大、光化学烧孔存储等方面的巨大潜力，近年来引起了人们的广泛关注。氟化物玻璃的常规制备工艺是对起始氟化物进行配料、熔融和淬火。然而，自几年前以来，已经尝试了各种氟化物玻璃的不同制备技术，以制备具有适合于有源光学器件的形状的玻璃。可以预见，采用溶胶-凝胶合成和反应气氛处理相结合的多步骤工艺可以制备可用作光波导用的单块氟化物玻璃薄膜。以金属醇盐为原料，以NF3气体为氟化气体，成功地制备了含稀土氟锆酸盐玻璃薄膜。然而，遗憾的是，人们发现，溶胶-凝胶和氟化相结合的工艺不足以制备光波导。因此，尝试了ECR微波等离子体CVD工艺作为替代工艺。该方法以金属β-二酮盐为起始原料，以NF3气体为氟化气体。成功地合成了ZrF_4-BaF_2-LnF_3(Ln=Pr，Eu，Er)玻璃薄膜。此外，通过观察掺Er的ZrF_4-BaF_2玻璃薄膜的上转换发光，证实了光波导的形成。

Recently much attention has been paid to rare-earth-containing fluoride glasses because of the high potentiality for active optical devices such as light delivery, fiber laser, optical frequency upconversion, optical amplification, photochemical hole burning memory and so on. A conventional preparation technique of fluoride glasses is batching, melting and quenching of the starting fluorides. Since several years ago, however, different preparation techniques have been attempted for various fluoride glasses to prepare glasses with forms suitable for active optical devices. It is anticipated that a multistep process incorporationg sol-gel synthesis and reactive atmosphere processing can be used to prepare momolithic fluoride glass films which can be used as optical waveguide. The present investigation succeeded in the preparation of rare-earth-containing fluorozirconate glass films by using metal alkoxides and an NF_3 gas as starting materials and a fluorination gas, respectively. Regretably, however, it was found that combined processes of sol-gel and fluorination is inadequate for preparing optical waveguide. Thus, an ECR microwave plasma CVD process was attempted as an alternative process. In this technique beta-diketonates of metals and an NF_3 gas were employed as starting materials and a fluorination gas, respectively. ZrF_4-BaF_2-LnF_3 glass films (Ln=Pr, Eu and Er) were successfully synthesized. Moreover the formation of optical waveguide was confirmed by observing the Er^<3+> upconversion luminescence of Er-doped ZrF_4-BaF_2 glass films.