Degenerate Four-Wave Mixing of Surface Plasmon Polaritons and Volume Waves in Au/VO2

We investigate experimentally the nonlinear degenerate four-wave mixing process with excitation of surface-plasmon polaritons (SPPs) in Au/VO2 composite structure. The ultrafast formation of transient grating in VO2 layer is accompanied by nonlinear wave interaction with SPPs excited by attenuated total reflection (ATR) coupler at Au/VO2 interface. Optical mixing of waves with same and different linear polarizations gives rise to surface plasmon wave by inducing a nonlinear polarization. Photoinduced diffraction grating in photorefractive layer is also used to decouple the SPPs from surface and to convert SPPs to volume optical wave, which was then directly detected by a photodetector. It is demonstrated a possibility of efficient tuning of enhancement, reflection and diffraction of optical waves in photorefractive Au/VO2 structure via excitation of surface plasmons within visible and near-infrared region. Nonlinear energy transfer between different types of waves with the ability to manipulate and decouple SPPs from the surface opens new possibilities for future plasmonics devices.