A photon avalanche (PA) effect that occurs in lanthanide-doped solids gives rise to a giant nonlinear response in the luminescence intensity to the excitation light intensity. As a result, much weaker lasers are needed to evoke such PAs than for other nonlinear optical processes. Photon avalanches are mostly restricted to bulk materials and conventionally rely on sophisticated excitation schemes, specific for each individual system. Here we show a universal strategy, based on a migrating photon avalanche (MPA) mechanism, to generate huge optical nonlinearities from various lanthanide emitters located in multilayer core/shell nanostructrues. The core of the MPA nanoparticle, composed of Yb³⁺ and Pr³⁺ ions, activates avalanche looping cycles, where PAs are synchronously achieved for both Yb³⁺ and Pr³⁺ ions under 852 nm laser excitation. These nanocrystals exhibit a 26th-order nonlinearity and a clear pumping threshold of 60 kW cm⁻². In addition, we demonstrate that the avalanching Yb³⁺ ions can migrate their optical nonlinear response to other emitters (for example, Ho³⁺ and Tm³⁺) located in the outer shell layer, resulting in an even higher-order nonlinearity (up to the 46th for Tm³⁺) due to further cascading multiplicative effects. Our strategy therefore provides a facile route to achieve giant optical nonlinearity in different emitters. Finally, we also demonstrate applicability of MPA emitters to bioimaging, achieving a lateral resolution of ~62 nm using one low-power 852 nm continuous-wave laser beam.

镧系元素掺杂固体中发生的光子雪崩 (PA) 效应导致发光强度对激发光强度的巨大非线性响应。因此，与其他非线性光学过程相比，唤起此类 PA 需要更弱的激光器。光子雪崩主要限于散装材料，并且通常依赖于复杂的激发方案，特定于每个单独的系统。在这里，我们展示了一种通用策略，基于迁移光子雪崩 (MPA) 机制，从位于多层核/壳纳米结构中的各种镧系元素发射体产生巨大的光学非线性。MPA纳米粒子的核心，由Yb ³⁺和Pr ^3+组成离子，激活雪崩循环循环，其中在 852 nm 激光激发下Yb ³⁺和 Pr ³⁺离子同步实现 PA 。这些纳米晶体表现出 26 阶非线性和 60 kW cm ^-2的清晰泵浦阈值。此外，我们证明了雪崩 Yb ³⁺离子可以将其光学非线性响应迁移到位于外壳层的其他发射器（例如，Ho ³⁺和 Tm ³⁺），从而产生更高阶的非线性（向上Tm ^{3+到 46 日}) 由于进一步的级联乘法效应。因此，我们的策略提供了一条在不同发射器中实现巨大光学非线性的简便途径。最后，我们还展示了 MPA 发射器在生物成像中的适用性，使用一根低功率 852 nm 连续波激光束实现了约 62 nm 的横向分辨率。