This paper by Handel, Hall, and Tournier discusses noise in THz detectors and generators, presented at the 2006 SPIE Defense and Security Symposium. The work provides comprehensive analysis of noise sources including quantum 1/f noise, thermal noise, generation-recombination noise, and technical noise in terahertz devices used for security screening, standoff chemical detection, biomedical imaging, and wireless communications, offering design guidelines for achieving optimal noise performance in emerging terahertz technologies for defense and commercial applications.