All-optical generation of static electric field in a single metal-semiconductor nanoantenna.

Electric field is a powerful instrument in nanoscale engineering, providing wide functionalities for control in various optical and solid-state nanodevices. The development of a single optically resonant nanostructure operating with a charge-induced electrical field is challenging, but it could be extremely useful for novel nanophotonic horizons. Here, we show a resonant metal-semiconductor nanostructure with a static electric field created at the interface between its components by charge carriers generated via femtosecond laser irradiation. We study this field experimentally, probing it by second-harmonic generation signal, which, in our system, is time-dependent and has a non-quadratic signal/excitation power dependence. The developed numerical models reveal the influence of the optically induced static electric field on the second harmonic generation signal. We also show how metal work function and silicon surface defect density for different charge carrier concentrations affect the formation of this field. We estimate the value of optically-generated static electric field in this nanoantenna to achieve ≈108V/m. These findings pave the way for the creation of nanoantenna-based optical memory, programmable logic and neuromorphic devices.

Thermo-optical reshaping of second-harmonic emission from dimer all-dielectric nanoresonators.

All-dielectric nanophotonics offers a wide range of possibilities for thermally induced light manipulation at the nanoscale. High quality resonances allow for efficient light-to-heat conversion supported by various temperature detection approaches based on thermally sensitive intrinsic optical responses. In this work, we study theoretically a phenomenon of the photothermal reshaping of the radiation pattern of second-harmonic generation (SHG) that occurs in resonant all-dielectric systems. In the suggested geometry, a near-IR pulsed laser is used for SHG while a continuous wave visible laser simultaneously heats the structure. The thermo-optical switching of the resonant optical states in the nanostructures governs the reconfiguration of the emission pattern, without significant loss in the magnitude of the SHG. We believe, that our findings will pave the way for subwavelength-size near-IR thermally switchable nonlinear optical devices.