Polarization switching of thermal emissions based on plasmonic structures incorporating phase-changing material Ge2Sb2Te5

The ability to control the polarization of thermal emissions is important for fundamental science and many applications such as multichannel infrared emitters and chemical sensing. Most previous works on controlling the polarization of thermal emission are based on changing geometric sizes of the structures. The active control remains elusive so far. Here, we propose a design to actively switch the polarization of thermal emission. A metal-insulator-metal plasmonic thermal emitter with phase changing material Ge2Sb2Te5 (GST) as the insulator is experimentally demonstrated. The thermal emitter with top GST and gold ellipses can excite third-order magnetic resonances with perpendicular polarization along both short radius and long radius. The polarization of the thermal emission can be rotated by 90° at 9.55 μm peak wavelength when GST phase changes from the amorphous phase to the 40% crystalline phase.