Polarization effects on heterodyne detection and imaging using Glow Discharge Detector at millimeter wavelengths

A miniature neon indicator lamp, also known as a Glow Discharge Detector (GDD), costing about 50 cents, was found to be an excellent room temperature THz radiation detector. Polarization effects on heterodyne detection were investigated in this work. In heterodyne detection, because of the dot product relationship between signal electric field (E_S) and local oscillator (LO) electric field (E_lo), optimal operation of heterodyne detection is obtained when E_S and E_lo are of the same polarization. Preliminary results at 300 GHz showed better sensitivity by a factor of 20 with only 56 microwatt local oscillator power using heterodyne compared to direct detection. Further improvement of the detection sensitivity can be achieved if the LO power (P_lo) is increased. In this work investigation of polarization effects in heterodyne detection using neon indicator lamp GDD was carried-out. Experimental results of heterodyne detection at 300 GHz showed that an intermediate frequency (IF) signal was obtained for orthogonal polarization of the LO and signal, in contradiction to the theory. Also, our latest imaging results using Glow Discharge Detector at millimeter wavelengths will be shown in this work.