The development of high-speed electronics has improved the availability and reduced the cost of components operating in the millimeter wave (MMW) region substantially. Therefore, in recent years the spectral range of 30–300 GHz has received a strongly increased interest in various application areas such as medical imaging, spectroscopy, radars, and guidance systems. The progress of MMW technologies has opened new opportunities in optical communication, and it has also made possible the rebirth of optical heterodyne detection systems.

Remote heterodyne detection (RHD) links are promising candidates for the optical MMW generation in the future. The most critical challenge in RHD links is the generation of two stable and phase-correlated laser lines. This work focuses on RHD links, and the generation of optical carriers using novel distributed feedback (DFB) laser diodes (LDs). These lasers provide a compact low cost solution for the optical MMW generation with a tunable frequency separation that can be exploited in numerous applications, particularly in RHD links.

The thesis gives a general presentation of optical communication links followed by a presentation of the elements and the characteristics of RHD links, outlining the diffculties and advantages of employing RHD links in optical communications. Multi-quantum-well distributed feedback laser diode principles and characteristics are reviewed and the LD requirements for operating as light sources in optical RHD links are derived. The thesis also presents a time-domain travelling wave simulation model developed for complex multi-section LDs. The model was developed since the laser characteristics needed for operating as RHD light sources imply non-typical simulation conditions like longitudinally non-uniform transverse sections, longitudinally non-uniform carrier and photon densities, variable gain and grating coupling coeffcient, and a combination of active and passive sections. The developed model takes into account spontaneous emission noise, gain dispersion and variations of the longitudinal effective refractive index, material gain, carrier densities and photon density. Based on this model a simulation program has been implemented. Numerous simulation studies have been performed on the novel laser structures and the thesis presents some of the most relevant numerical modelling results, including continuous wave and transient analysis. The simulation results are compared with experimental results and the differences are analyzed and discussed.