Microfabricated Traveling Wave Tubes for High Power Millimeter-Wave and THz-regime Sources

The millimeter-wave (MMW) and terahertz (THz)-regime portions of the electromagnetic spectrum have enormous application potential, including high-data-rate communications, remote sensing and threat detection, high resolution radar, biomedical imaging, and spectroscopic analysis. To exploit this potential, new sources of coherent electromagnetic radiation are needed in the frequency range of 100 - 1000 GHz. The ideal sources would provide high power with high efficiency in a compact, lightweight, and low-cost package. Many of the applications require bandwidths of several percent (relative) or greater and both amplifiers and oscillators are needed. Vacuum electronic devices, such as traveling wave tubes (TWTs) meet many of these requirements but are constrained by complex fabrication methods that become impractical at frequencies of 100 GHz and above. This research is investigating new methods for TWT fabrication, derived from semiconductor microfabrication technologies. Various microfabrication techniques are under investigation, to identify those that are optimally suited. One critical piece of research is to measure the passive microwave losses of a 400 GHz waveguide made by these microfabrication methods. The final goal includes a study of the characteristics of a microfabricated TWT using a new electron-beam source designed for MMW and THz-regime vacuum device research