Tailoring Infrared Refractory Plasmonic Material to Broadband Circularly Polarized Thermal Emitter

Circularly polarized (CP) thermal emission possesses huge application value in the fields of infrared detecting and polarimetric thermal imaging; however, the naturally occurring infrared source is incoherent and unpolarized. In this paper, we designed a broadband CP source adaptive for high temperature in consideration of the collision frequency of the electrons increasing with temperature. Compared with the structure proposed before, “I”-shaped resonators based on refractory plasmonic material generate the linearly polarized (LP) emission and the dielectric quarter-wave plate enhances the degree of emitted CP by suppressing the parasitic radiation. More than 80 % right-handed circularly polarized (RCP) emissivity in wavelengths ranging from 3.28 to 4.81 μm within 706 to 884 K is theoretically achieved.