| A submillimeter wavelength test facility has been established. The facility includes two independent far infrared lasers, two Martin-Puplett diplexers, a low noise IF receiver, far infrared power meters and various electronic test equipment. The capabilities include reliable measurement of video responsivity and receiver noise temperature as high as 200,000 K. The measurements have been computerized to improve accuracy and provide faster data acquisition.;We have obtained state-of-the-art results for room temperature heterodyne receivers at THz frequencies. This study has investigated several diodes (fabricated at the University of Virginia Semiconductor Device Laboratory) with a range of junction capacitance and epitaxial layer doping. The lowest capacitance diode, the 1T15;Highly doped diodes (;We have found that the ;From this study, several important conclusions can be drawn. The diodes are shot noise limited at the normal bias current used for mixing. However this noise is about 40% higher than expected by theory. Elimination of this excess noise would lead to a significant improvement in receiver sensitivity. The parasitic elements, ;From these results, it is expected that receiver performance in the 1 to 2.5 THz frequency range can be improved significantly by eliminating excess noise, further increasing the... |
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