An array of monolithically fabricated nanoklystrons has been proposed as a frequency-agile and/or redundant source of electromagnetic radiation at frequencies ranging from about 0.3 to about 3 THz. Each nanoklystron would, as its name suggests, be a very small klystron. Like other klystrons, a nanoklystron would operate at a frequency determined primarily by the dimensions of its resonant cavity and the spacing of its electron-bunching grids, with some dependence on applied voltages. An individual nanoklystron could be fabricated in top and bottom halves from silicon wafers and would contain an integral output waveguide and feed horn (see Figure 1). In typical operation, a nanoklystron without a mechanical tuner would generate power only at a fixed frequency. Thus, frequency agility and/or redundancy could be obtained by incorporating into the array multiple nanoklystrons that are pretuned to generate signals at all required frequencies.
The array of nanoklystrons would be fabricated in substantially the same manner as that of a single nanoklystron, except that the nanoklystrons would be spaced at angular intervals near the periphery of the wafer. The output port of each nanoklystron would then be oriented along the edge of the wafer (see Figure 2). Each nanoklystron would be fabricated to oscillate at a different predetermined frequency within the desired output band. A particular frequency would be selected by indexing the wafer.
The dimensions of silicon wafers [the present industry standard diameter is 8 in. (≈20 cm)] and the horn dimensions required for operation in the intended submillimeter wavelength range are compatible with making thousands of nanoklystrons on a single wafer in a single production run. Contact pads for supplying power to individual klystrons could be formed on the top and bottom of the disk, and registration notches could be formed at corresponding angular locations on the top or bottom of the disk; this would make it possible to simply rotate the disk to a detent at a designated angular position in order to obtain radiation at the frequency of the nanoklystron at that position. The contacts and detents would be arranged so that the feed horn of the selected nanoklystron would be in the proper position for output coupling.
This work was done by Peter Siegel of Caltech for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Electronics & Computers category.
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Refer to NPO-21033, volume and number of this NASA Tech Briefs issue, and the page number.