Smeets S, Maes B, Rosolen G
Micro- and Nanophotonic Materials Group, Research Institute for Materials Science and Engineering, University of Mons, 20 Place du Parc, 7000, Mons, Belgium.
Discov Nano. 2024 Sep 27;19(1):155. doi: 10.1186/s11671-024-04111-8.
In the vicinity of plasmonic nanostructures that support highly confined light fields, spontaneous emission processes, such as two-photon spontaneous emission (TPSE), exhibit higher-order multipolar emission pathways beyond the dipolar one. These multipolar emission channels occur simultaneously and can interfere with each other. We develop a novel framework that computes these interference effects for TPSE of a quantum emitter close to an arbitrary nanostructure. The model is based on the computation of Purcell factors that can be calculated with conventional electromagnetic simulations, which avoids complex analytic calculations for the environment. For a transition of a hydrogen-like emitter close to a graphene nanotriangle, we demonstrate a breakdown of the dipolar selection rule in the TPSE process. This breakdown is due to a huge enhancement of the two-electric dipole (2ED) and of the two-electric quadrupole (2EQ) transitions. We observe an important interference between these multipolar transitions, as it increases the total rate by . In the end, our framework is a complete tool to design emitters and nanostructures for TPSE, where the exploitation of previously ignored interference effects provides an additional degree of freedom, for example to boost desired transitions and to supress undesirable ones.
在支持高度受限光场的等离子体纳米结构附近，自发发射过程，如双光子自发发射（TPSE），展现出超越偶极子的高阶多极发射路径。这些多极发射通道同时发生且会相互干扰。我们开发了一种新颖的框架，用于计算靠近任意纳米结构的量子发射器的TPSE的这些干涉效应。该模型基于珀塞尔因子的计算，而珀塞尔因子可通过传统电磁模拟来计算，这避免了对环境进行复杂的解析计算。对于靠近石墨烯纳米三角形的类氢发射器的跃迁，我们展示了TPSE过程中偶极选择规则的失效。这种失效是由于双电偶极（2ED）和双电四极（2EQ）跃迁的大幅增强。我们观察到这些多极跃迁之间存在重要的干涉，因为它使总速率提高了 。最后，我们的框架是用于设计TPSE的发射器和纳米结构的完整工具，其中利用先前被忽略的干涉效应提供了一个额外的自由度，例如增强所需跃迁并抑制不需要的跃迁。
