Tunable third-harmonic generation using low-loss phase change chalcogenides

We demonstrate a new platform for reconfigurable third-order nonlinear photonic devices formed by silicon dioxide (SiO2)-Sb2S3(Sb2Se3)-SiO2 subwavelength Fabry-Perot cavities on a gold (Au) reflector, which exhibit giant third-harmonic generation (THG) modulations with enhanced efficiency. The use of the phase-change dichalcogenides (Sb2S3 or Sb2Se3) enables a wide tuning range of the THG response. The devices work at dispersion-engineered THG resonances at the crystalline phase (c-phase) of the PCC, which numerically exhibit c-phase THG flows a few 100 times more than those at the amorphous phase (a-phase) of the PCC at near-infrared excitation wavelengths.