Semiconductor materials biased with a static magnetic field are used here to design and analyze several nonreciprocal devices that can operate above 30 GHz and into the terahertz range. These devices overcome some limitations of biased ferrites in terms of frequency, bandwidth, compatibility with the monolithic-microwave-integrated-circuits technology, and the required magnetic bias magnitude.
In this dissertation, simulated results will be provided for several practical bulk and planar devices operating at room and liquid-nitrogen temperatures. The main structures that are being used are based on a longitudinally-biased coaxial waveguide, and a transversely-biased slotline waveguide. These two types of waveguiding structures were extensively studied under the influence of changing frequency, static bias, and device parameters. A long list of features accompanied the design of these devices, which, to the best knowledge of the author, are reported here for the first time and would facilitate the adoption of magnetoplasma-based devices to a variety of applications.
The semiconductor materials are carefully modeled and introduced into Maxwell's equations by means of Drude's model. The loss mechanism in the magnetized plasma was taken into account due to its huge impact on the devices efficiency and overall performance. Based on a modified commercial finite element method code, two-dimensional eigenmode simulations as well as three-dimensional models are used as primary tools to illustrate the phenomena, analyze and optimize the devices, and demonstrate their operation.
This dissertation concludes with a detailed study of surface plasmons and their relation to the well-known volumetric waveguide modes through a generalized microscale model of metals that is valid from DC to optical frequencies.