Preparation and Spectral Properties of Er,Na∶CaF_(2) Transparent Ceramics

Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in thickness.The average grain size of the obtained Er,Na∶CaF_(2) powders varied from 28 nm to 36 nm with the shape of sphere.The effects of Na^(+) doping on the transmittance,microstructure and spectral properties of Er^(3+)∶CaF_(2) transparent ceramics were investigated.The transmittance of all the obtained ceramic samples is above 84%in the wavelength of 1000 nm.The results show that after introducing Na^(+)into Er^(3+)∶CaF_(2) transparent ceramics,charge-neutralized Er^(3+)-Na^(+) structure formed which prevent Er^(3+) from clustering.The emission spectra of Er^(3+) in CaF_(2) transparent ceramics at around 1.5 and 2.7μm could be modulated by adjusting the concentration of Na^(+) and the near-infrared fluorescence lifetime at around 1.5μm increase with the increasing of Na^(+) concentration,reaching a maximum of 56.75 ms.

氟化钙晶体缺陷对应力双折射影响机制的研究

氟化钙(CaF2)晶体具有紫外透过率高(>99%@193 nm)、抗激光损伤阈值高等特点,在高功率紫外激光器、深紫外光刻机等领域具有广泛的应用。应力双折射是氟化钙晶体在实际应用中的关键性能指标,会导致通过晶体的光束发生形变,严重影响成像质量。采用坩埚下降法制备了尺寸为φ210 mm的氟化钙晶体,系统研究了CaF2晶体的位错和小角度晶界以及结晶质量对晶体应力双折射的影响,实验结果表明,位错密度的增高、小角度晶界的聚集、结晶质量的变差,会引起局部残余应力的集中,加剧应力双折射现象。

Er:Sr_(5)(PO_(4))_(3)F透明陶瓷的制备和上转换光学性能

随着激光二极管朝着小型化和高度集成化目标的不断发展,包括Sr_(5)(PO_(4))_(3)F (S-FAP)在内的一些热管理性能一般的晶体材料开始重新进入研究者的视野。本研究采用共沉淀法合成了2%(摩尔分数) Er^(3+):S-FAP多晶纳米粉体,通过热压烧结合成出光学性能优异的Er:S-FAP透明陶瓷,并对Er:S-FAP多晶纳米粉体和透明陶瓷进行了表征。结果表明:2%Er^(3+):S-FAP粉体和陶瓷的物相结构都符合六方晶系氟磷灰石结构,没有观察到异常杂质峰。2%Er^(3+):S-FAP粉体整体呈现出分散性优良的短棒状外观,其平均晶粒尺寸为(19.10±1.6) nm。对应陶瓷的平均晶粒尺寸为386.6±20.8 nm,断面和表面微观结构都呈现出均匀致密的特征。2%Er^(3+):S-FAP透明陶瓷在500 nm和1 000 nm波长处的线性光学透过率分别达到了66.14%和84.41%。Er^(3+)在S-FAP陶瓷中的主要的发射峰位于550 nm和661 nm,分别对应绿色光和红色光的发射,红绿光的上转换发光是由双光子吸收过程决定,最后陶瓷在550 nm波长位置的荧光寿命为2.1μs。