Developments of narrow gap semiconductor physics have been closely related to the development of the science and technology of infrared optical electronics in which narrow gap semiconductors have played a vital role in detectors and emitters, and other high speed devices. Antimony-based technology is very promising for low voltage millimeter-wave (mm-wave) integrated circuits (ICs), as well as very highspeed, low-power digital ICs. Among the many potential applications are digitally beam-steered phased array receivers, particularly those deployed in space; 80-160 Gbit/s optical communication systems; unmanned reconnaissance vehicles; and mobile, battery-powered systems.