Optical frequency combs are used for metrology, absolute frequency measurement, remote sensing, THz generation, microwave photonics and coherent optical communications. The ideal method for comb generation depends on the target application. While Mode-locked lasers can generate ps pulse trains with repetition rates of tens of GHz that are useful for Optical-Time Domain Multiplexing, combs for optical communications are usually generated by using electro-optical modulators. Recently gain switching of single-mode semiconductor lasers has appeared as an alternative to electro-optical modulation due to the lower cost and complexity of the transmitter.

The objective of this project is to study, both from a theoretical and experimental point of view, the characteristics of frequency combs generated by semiconductor lasers. Different types of semiconductor lasers and techniques will be used to generate frequency combs: from mode-locked lasers to gain-switching of semiconductor lasers like VCSELs, discrete model lasers, DFBs, and multi-section lasers. Novel techniques, such as optical injection, will be introduced to improve the frequency comb characteristics. Combs generated by using different techniques and devices will be evaluated and compared. Optimization of the comb characteristics relevant for applications in THz generation, microwave photonics, optical communications and remote sensing will be performed.