Nonlinear core-shell Yagi-Uda nanoantenna for highly tunable directive emission

We propose a novel type of tunable Yagi-Uda nanoantenna composed of metal-dielectric (Ag-Ge) core-shell nanoparticles. By choosing the appropriate nanoantenna parameters we excite a Van Hove singularity, supporting high values of directivity and Purcell factor within the same narrow frequency range. Our analysis reveals the possibility of flexible dynamical tuning of the hybrid nanoantenna emission pattern via electron-hole plasma excitation by additional fs-laser signal pulses.