Abstract
The terahertz (THz) region occupies a large portion of the electromagnetic spectrum, located between the microwave and
optical frequencies and normally is defined as the band ranging from 0.1 to 10 THz. In recent years, this intermediate
THz radiation band has attracted considerable interest, because it offers significant scientific and technological potential
for applications in many fields, such as sensing [1], imaging [2] and spectroscopy [3]. However, waveguiding in this
intermediate spectral region is a major challenge and strong dielectric and conductive losses in the terahertz frequency
range have been a major problem for waveguiding. The conventional guiding structures exemplified by microstrips,
coplanar striplines and coplanar waveguides [4] are highly lossy and dispersive. However, so far the most promising
dielectric waveguides have been the use of photonic crystal fibers at terahertz frequencies [5, 6] and metal coated guides
[7] at terahertz frequencies. In this paper, various types of practical dielectric and metal coated waveguides are evaluated
and design optimization of Quantum Cascade Lasers, MMI-based power splitters and narrow-band filters are presented,
by using full-vectorial finite element method [8].
