29 Sep '12, 3pm

The Truth About Terahertz via @IEEESpectrum

That low efficiency combined with the devices’ small size leads to another problem: extremely high power densities (the amount of power the devices must handle per unit area) and current densities (the amount of current they must handle per unit area). For the vacuum and solid-state devices, the power densities were in the range of several megawatts per square centimeter. Suppose you want to use a conventional vacuum traveling-wave tube, or TWT, that’s been scaled up to operate at 1 THz. Such an apparatus would require you to focus an electron beam with a power density of multiple megawatts per square centimeter through an evacuated circuit having an inner diameter of 40 µm—about half the diameter of a human hair. (The solar radiation at the surface of the sun, by contrast, has a power density of only about 6 kilowatts per square centimeter.) A terahertz transistor, with i...

Full article: http://spectrum.ieee.org/aerospace/military/the-truth-abo...

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