Boccolini Alessandro, Favilla Elena, Tonelli Mauro, Richards Bryce S, Thomson Robert R
Opt Express. 2015 Jul 27;23(15):A903-15. doi: 10.1364/OE.23.00A903.
This manuscript presents a study of the upconversion (UC) in barium yttrium fluoride (BaY2F8) single crystal doped with trivalent erbium ions (Er3+) under excitation of the 4I(13/2) level at three different wavelengths: 1493 nm, 1524 nm and 1556 nm. The resulting UC emission at around 980 nm has been investigated and it has been found that a thickness optimization is required to reach high quantum yield values, otherwise limited by self-absorption losses. The highest external photoluminescence quantum yield (ePLQY) measured in this study was 12.1±1.2 % for a BaY2F8:30at%Er3+ sample of thickness 1.75±0.01 mm, while the highest internal photoluminescence quantum yield (iPLQY) of 14.6±1.5 % was measured in a BaY2F8:20at%Er3+ sample with a thickness of 0.49±0.01 mm. Both values were obtained under excitation at 1493 nm and an irradiance of 7.0±0.7 Wcm(-2). The reported iPLQY and ePLQY values are among the highest achieved for monochromatic excitation. Finally, the losses due to self-absorption were estimated in order to evaluate the maximum iPLQY achievable by the upconverter material. The estimated iPLQY limit values were ∼19%, ∼25% and ∼30%, for 10%, 20% and 30% Er3+ doping level, respectively.
本手稿介绍了一种在掺有三价铒离子（Er3+）的氟化钡钇（BaY2F8）单晶中，在4I(13/2)能级分别在1493 nm、1524 nm和1556 nm三个不同波长激发下的上转换（UC）研究。对约980 nm处产生的上转换发射进行了研究，发现需要进行厚度优化以达到高量子产率值，否则会受到自吸收损耗的限制。在本研究中，对于厚度为1.75±0.01 mm的BaY2F8:30at%Er3+样品，测得的最高外部光致发光量子产率（ePLQY）为12.1±1.2%，而对于厚度为0.49±0.01 mm的BaY2F8:20at%Er3+样品，测得的最高内部光致发光量子产率（iPLQY）为14.6±1.5%。这两个值都是在1493 nm激发和7.0±0.7 Wcm(-2)的辐照度下获得的。所报道的iPLQY和ePLQY值是单色激发所能达到的最高值之一。最后，估算了自吸收引起的损耗，以评估上转换材料可实现的最大iPLQY。对于10%、20%和30%的Er3+掺杂水平，估算的iPLQY极限值分别约为19%、25%和30%。
