Experimental Study of Polarization Characteristics of Terahertz Emission

In this article, we present an experimental study of the polarization characteristics of the emission intensity from the surface of a material using terahertz (THz) passive measurements. We developed an experimental system and method to measure the intensity of a sample at several emission angles with vertical and horizontal polarization relative to the plane of the sample surface within a 5 K error in the brightness temperature. Emissions at 280 and 490 GHz wavebands were measured using subharmonic mixer receivers with Schottky barrier diodes operating at room temperature. We measured the intensity of radiation from a magnetic substance-loading material called MF110, which is used as a calibration hot load of THz radiometers because of its low reflectivity and light weight. Although the experimental conditions limited the range of the emission angle and temperatures of the sample and experimental system, it was confirmed that the polarization characteristics of the emission at each emission angle were in accordance with the Fresnel equations. Because the optical system in the experiment used a polarization rotator and a movable ellipsoidal mirror that enabled the receiver to remain stable, a highly sensitive system to measure sample emission was developed.