Temperature Dependent Polarization of Thermal Radiation Emitted by hot Tungsten Wires

The properties of thermal emission of hot bodies is a central topic in Modern Physics [1]. The dependence of the Planck’s law only on the body temperature T but not on its material properties make pirometry a universal pyrometric technique [2]. The blackbody emission consists of unpolarized, incoherent radiation for bodies whose size is larger than the typical thermal wavelength, λT = hc/kBT, where h, c and kB are the Planck’s constant, speed of light, and Boltzmann’s constant, respectively. However, if the radiator dimensions are of the order of λT or smaller, thermal radiation shows a high degree of spatial and temporal coherence in the near-field region, and shows a quite large degree of polarization. Thin wires are thus very suitable objects to study the polarization properties of thermal radiation [3, 4]. For wires whose radius is r > 1.5λT , the emitted radiation is linearly polarized in a direction perpendicular to the wire axis [5, 6].