Rare-earth-doped upconversion nanoparticles are attracting considerable attention because of their stable, coherent, narrowband and multi-colour luminescence, which features less dephasing effects, crosstalk, photo-blinking and photo-bleaching compared with quantum dots and organic dyes. However, due to the 4f–4f forbidden transitions of rare-earth ions, upconversion nanoparticles exhibit long luminescence decay times, ranging from microseconds to milliseconds, restricting their application in time-dependent nanophotonic devices. Here we fabricate a tilted plasmonic nanocavity to shorten the luminescence decay time of a rare-earth-doped nanoparticle to sub-50 ns while maintaining high quantum efficiency enhancement, tunable polarization-dependent and far-field directional emissions and selective polychromatic chirality. We expect this new type of ultrafast, directional and polarized luminescence of a rare-earth-doped nanoparticle to vigorously promote the development of coherent single-photon sources, quantum communications and nanolasers.

稀土掺杂上转换纳米粒子因其稳定、相干、窄带和多色发光而备受关注，与量子点和有机染料相比，其具有较少的相移效应、串扰、光闪烁和光漂白等特点。然而，由于 4 f –4 f由于稀土离子的禁跃跃迁，上转换纳米粒子表现出较长的发光衰减时间，从微秒到毫秒不等，限制了它们在时间相关的纳米光子器件中的应用。在这里，我们制造了倾斜的等离子体纳米腔，以将稀土掺杂纳米粒子的发光衰减时间缩短至 50 ns 以下，同时保持高量子效率增强、可调谐的偏振相关和远场定向发射以及选择性多色手性。我们预计这种新型的稀土掺杂纳米粒子的超快、定向和偏振发光将大力推动相干单光子源、量子通信和纳米激光器的发展。