Frequency-controlled sources of far-infrared radiation for spaceborne applications

Among the difficulties in developing far-infrared (FIR) technology, a perennial lack of frequency-controlled sources has kept this spectral region´s technology far behind that of the surrounding spectral regions. However, as is the case in other spectral regions, astronomers and atmospheric scientists drive much of the cutting-edge technology development in the FIR. The dramatic attenuation of FIR radiation by water and other constituents of the Earth´s atmosphere forces many of the scientists´ measurement platforms above the atmosphere, into space. Therefore, there is a strong correlation between the development of new FIR technology and spaceborne instrumentation. In this paper, we address the needs of the FIR space-flight community, providing an introduction to the common heterodyne receiver configurations and the state of technology for various front-end components. We make frequent reference to the added challenges of producing such receivers for space environments