The integration of metallic plasmonic nanoantennas with quantum emitters can dramatically enhance coherent harmonic generation, often resulting from the coupling of fundamental plasmonic fields to higher-energy, electronic or excitonic transitions of quantum emitters. The ultrafast optical dynamics of such hybrid plasmon–emitter systems have rarely been explored. Here, we study those dynamics by interferometrically probing nonlinear optical emission from individual porous gold nanosponges infiltrated with zinc oxide (ZnO) emitters. Few-femtosecond time-resolved photoelectron emission microscopy reveals multiple long-lived localized plasmonic hot spot modes, at the surface of the randomly disordered nanosponges, that are resonant in a broad spectral range. The locally enhanced plasmonic near-field couples to the ZnO excitons, enhancing sum-frequency generation from individual hot spots and boosting resonant excitonic emission. The quantum pathways of the coupling are uncovered from a two-dimensional spectrum correlating fundamental plasmonic excitations to nonlinearly driven excitonic emissions. Our results offer new opportunities for enhancing and coherently controlling optical nonlinearities by exploiting nonlinear plasmon-quantum emitter coupling.

金属等离激元纳米天线与量子发射器的集成可以显着增强相干谐波的产生，这通常是由于基本等离激元场与量子发射器的高能，电子或激子跃迁耦合所致。这种混合等离激元-发射体系统的超快光学动力学很少被研究。在这里，我们通过干涉法探测来自渗透有氧化锌（ZnO）发射器的单个多孔金纳米海绵的非线性光学发射，研究了这些动力学。几飞秒的时间分辨光电子发射显微镜显示，在随机无序纳米海绵的表面上存在多个在宽光谱范围内共振的长寿命局部等离激元热点模式。局部增强的等离激元近场耦合到ZnO激子，增强各个热点产生的和频，并增强共振激子发射。耦合的量子路径是从二维频谱中发现的，该二维频谱将基本的等离子体激元激发与非线性驱动的激子发射相关联。我们的结果为利用非线性等离激元-量子发射体耦合提供了增强和相干控制光学非线性的新机会。