Abstract

At frequencies above 100 GHz, the generation and control of coherent radiation is greatly hindered by ohmic loss in semiconductors and metals and by higher-order mode generation in metallic waveguides and coplanar transmission lines. This paper deals with quasi-optical techniques, which are well suited for resonant-tunneling diodes (RTDs) in applications between 100 GHz and 1 THz. For example, semiconfocal open cavities have been used to suppress the phase noise and stabilize the frequency of RTD oscillators up to 200 GHz. Open cavities have also been proposed as a means of synchronizing N-element focal-plane arrays of RTDs, which would produce approximately N times the power of a single device. Finally, open cavities and dielectric waveguides are being analyzed as means of supporting a new type of source—the RTD relaxation oscillator. This source, like the focal-plane array, should have operating characteristics superior to those of the conventional RTD oscillator.

© 1992 Optical Society of America