The generation of anti-Stokes emission through lanthanide-doped upconversion nanoparticles is of great importance for technological applications in energy harvesting, bioimaging and optical cryptography1-3. However, the weak absorption and long radiative lifetimes of upconversion nanoparticles may significantly limit their use in imaging and labelling applications in which a fast spontaneous emission rate is essential4-6. Here, we report the direct observation of upconversion superburst with directional, fast and ultrabright luminescence by coupling gap plasmon modes to nanoparticle emitters. Through precise control over the nanoparticle's local density of state, we achieve emission amplification by four to five orders of magnitude and a 166-fold rate increase in spontaneous emission. We also demonstrate that tailoring the mode of the plasmonic cavity permits active control over the colour output of upconversion emission. These findings may benefit the future development of rapid nonlinear image scanning nanoscopy and open up the possibility of constructing high-frequency, single-photon emitters driven by telecommunication wavelengths.

中文翻译：

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上转换超短脉冲的寿命不到2μs。

通过镧系元素掺杂的上转换纳米粒子产生反斯托克斯发射对于能量收集，生物成像和光学密码学1-3中的技术应用非常重要。但是，上转换纳米粒子的吸收较弱且辐射寿命长，可能会极大地限制其在成像和标记应用中的使用，在这些应用中，快速自发发射率是必不可少的4-6。在这里，我们报告通过将间隙等离子体激元模式耦合到纳米粒子发射体上，直接观察到具有方向性，快速和超亮发光的上转换超爆发。通过精确控制纳米粒子的局部状态密度，我们将发射放大了4到5个数量级，自发发射速率提高了166倍。我们还证明，调整等离激元腔的模式可以对上转换发射的颜色输出进行主动控制。这些发现可能有益于快速非线性图像扫描纳米技术的未来发展，并开辟了构建由电信波长驱动的高频单光子发射器的可能性。