The ability to engineer nonlinear optical processes in all-dielectric nanostructures is both of fundamental interest and highly desirable for high-performance, robust, and miniaturized nonlinear optical devices. Herein, we propose a paradigm for the efficient tuning of a second-harmonic generation (SHG) process in dielectric nanoantennas by integrating with chalcogenide phase-change material. In a design with ${\mathrm{Ge}}_2{\mathrm{Sb}}_2{\mathrm{Te}}_5$ (GST) film sandwiched between the AlGaAs nanoantennas and ${\mathrm{AlO}}_x$ substrate, the nonlinear SHG signal from the AlGaAs nanoantennas can be boosted via the resonantly localized field induced by the optically induced Mie-type resonances, and further modulated by exploiting the GST amorphous-to-crystalline phase change in a nonvolatile, multilevel manner. The tuning strategy originates from the modulation of resonant conditions by changes in the refractive index of GST. With a thorough examination of tuning performances for different nanoantenna radii, a maximum modulation depth as high as $540\%$ is numerically demonstrated. This work not only reveals the potential of GST in optical nonlinearity control, but also provides a promising strategy in smart designing of tunable and reconfigurable nonlinear optical devices, e.g., light emitters, modulators, and sensors.

• Received 24 September 2021
• Revised 12 November 2021
• Accepted 15 November 2021

DOI:https://doi.org/10.1103/PhysRevB.104.195428