Development of Upconversion Material with Higher Efficiency

一些稀土离子，如Er^<3+>, Ho^<3+>, Tm^<3+>, Pr^<3+>和Nd^<3+>，当加入到合适的主晶格中时，可以将红外光上转换为可见光。这种上转换现象受到广泛关注，主要是因为用于红外探测器或短波长上转换激光器的光学器件需要抽运近红外光的可见光源。本研究取得的显著结果如下：在含氟玻璃中，我们发现在1erf_3 - 48inf_3 - 24pb_2 - 24baf_2 - 3laf_3组成的IPBL玻璃，其声子能量仅为270 cm^<-1>，此时的上转换效率最高。另一个重要的目标是在室温下演示连续波激光。由于光纤具有长长度的光约束能力，因此被认为是连续波室温上转换激光的可能候选材料。我们发现了连续波室温上转换激光器。由于所采用的泵浦波长存在于红外（800nm）附近区域，且该区域具有高功率激光二极管，与红外激光二极管组合而成的全固态绿色器件可应用于光数据存储、海底通信和投影电视等领域，因此研究Er3+掺杂光纤的上转换激光器具有很大的吸引力。我们发现，当用647 nm的红色氪激光泵浦时，Tm^<3+>掺杂的氟化玻璃在室温下显示出蓝光和紫外光。随后，我们发现Pr^<3+>掺杂的氟化物光纤在波长为800nm-1000nm的红外光泵浦下呈现出绿色、黄色和红色的光。

Some rare earth ions such as Er^<3+>, Ho^<3+>, Tm^<3+>, Pr^<3+> and Nd^<3+> when incorporated into a suitable host lattice, can upconvert infrared light to visible one. This upconversion phenomenon receives much interest, mainly because the visible source pumped in the near infrared light is required for optical devices which are used for the infrared light detector or the short wavelength upconversion laser. The remarkable result obtained in this study is following.1. Among fluoride glasses, we found that IPBL glass in the composition of 1ErF_3-48InF_3-24PbF_2-24BaF_2-3LaF_3, phonon energy of which is only as small as 270 cm^<-1> showed the highest upconversion efficiency at this moment.2. Another important objective is to demonstrate CW lasing at room temperature. It is considered that the optical fiber is a possible candidate of CW room temperature upconversion lasing material, because of its ability of light confinement over long lengths. We have found the CW room temperature upconversion lasing. Study of upconversion lasing of Er3+-doped fiber is attractive, since the pumping wavelength employed exists at around infrared (800nm) region where the high power laser diode is available and all-solid-state green devices based on a combination with the infrared laser diode might be applied for optical data storage, undersea communications and projection televisions.3. We have found that Tm^<3+>-doped fluoride glass showed blue and ultraviolet light at room temperature when pumped with a red krypton laser of 647 nm. Subsequently, We have found that Pr^<3+>-doped fluoride fibers exhibited green, yellow and red lights when pumped with infrared light of 800nm-1000nm wavelength.