Dynamically manipulating third-harmonic generation of phase change material with gap-plasmon resonators.

Here we theoretically demonstrate a dynamic third-harmonic generation (THG) device by incorporating chalcogenide phase change material (Ge2Sb2Te5) into ultra-small cavities of gap-plasmon resonators. Through coupling to plasmonic resonances, the THG efficiency of Ge2Sb2Te5 is increased up to five orders of magnitude due to the greatly enhanced electromagnetic fields within the ultra-small cavities. More interestingly, the THG signals of the proposed device can be dynamically switched on and off by tuning the phase states of Ge2Sb2Te5 between amorphous and crystalline. Our proposed dynamic THG nanostructures are beneficial to developing dynamic nonlinear nanophotonic devices.