Dual-wavelength orthogonally polarized radiation generated by a tungsten thermal source

Developing controllable radiation sources in the mid-infrared spectral region is significant in photonics technology because of rare available resources. Based on the thermal emission from a one-dimensional shallow tungsten grating, we propose a two-dimensional orthogonally-crossed shallow grating to produce an orthogonally-polarized dual-wavelength radiation with the emissivity as high as 78% and 91% from a single surface. The simulation shows that the field is intensively concentrated in vicinity of the air-tungsten interface when surface plasmon polaritons are excited. In addition, by optimizing the geometric parameters of the grating, the field is found to be more concentrated which leads to higher emissivity. The two wavelengths can be produced independently or simultaneously, depending on the polarization of the picking-up polarizer. Our investigations can help us developing controllable multi-wavelength thermal radiation sources from a single surface.