Tunable phase change polaritonic perfect absorber in the mid-infrared region

Realizing tunable light-polaritons interaction, such as perfect absorption in a controllable and compact manner holds great promise in nanophotonic systems. In this work, we engineer the hyperbolic surface phonon polaritons and surface plasmons polaritons to dynamically tune the perfect absorption in mid-infrared by combing the two van der Waals materials: the natural hyperbolic material hBN and phase change material VO₂. Two spectrally separated and physically distinct perfect absorption peaks are alternatively observed and can be tuned through changing the temperature. The absorption in the resonant wavelengths can reach around 100%. We also demonstrate the flexibility of the absorber by investigating the absorption dependence on the polarization state and angle of incidence. The structural parameters sweep also confirms the robustness of our design. Our findings may open new possibilities to many versatile minimized applications such as optical modulators, optical switching, and temperature control system.