Institute for Lasers, Photonics, and Biophotonics, The State University of New York at Buffalo, Buffalo, New York 14260, United States.
ACS Nano. 2011 Jun 28;5(6):4981-6. doi: 10.1021/nn201083j. Epub 2011 May 13.
We report intense upconversion photoluminescence (PL) in colloidal LiYF(4):Er(3+) nanocrystals under excitation with telecom-wavelength at 1490 nm. The intensities of two- and three-photon anti-Stokes upconversion PL bands are higher than or comparable to that of the Stokes emission under excitation with low power density in the range 5-120 W/cm(2). The quantum yield of the upconversion PL was measured to be as high as ∼1.2 ± 0.1%, which is almost 4 times higher than the highest upconversion PL quantum yield reported to date for lanthanide-doped nanocrystals in 100 nm sized hexagonal NaYF(4):Yb(3+)20%, Er(3+)2% using excitation at ∼980 nm. A power dependence study revealed that the intensities of all PL bands have linear dependence on the excitation power density, which was explained by saturation effects in the intermediate energy states.
我们在报告中指出，在使用 1490nm 的电信波长进行激发时，胶体 LiYF(4)：Er(3+)纳米晶体表现出强烈的上转换光致发光（PL）。在 5-120 W/cm(2)的低功率密度激发下，双光子和三光子反斯托克斯上转换 PL 带的强度高于或可与斯托克斯发射强度相媲美。上转换 PL 的量子产率被测量为高达约 1.2 ± 0.1%，这几乎是迄今为止报道的在 100nm 尺寸的六方 NaYF(4)：Yb(3+)20%、Er(3+)2%中掺杂镧系元素纳米晶体在使用约 980nm 激发时的最高上转换 PL 量子产率的 4 倍。功率依赖研究表明，所有 PL 带的强度与激发功率密度呈线性关系，这可以通过中间能级的饱和效应来解释。
