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.