Frequency- and amplitude- modulated semiconductor laser frequency combs

Chip-scale coherent semiconductor light sources generating optical frequency combs currently revolutionize mid-infrared on-chip spectroscopy, near-infrared optical communications and nonlinear microscopy. Their key advantages is the efficient generation of narrow and equidistant spectral lines or laser modes with a fixed phase relationship across a broadband spectral region. An attractive realization of such combs is based on nanostructured semiconductor lasers with semiconductor quantum dots forming their active region. In this thesis, frst, the formation of two types of optical frequency combs in a semiconductor quantum dot laser is presented: in-phase synchronization of the intermode beatings, leading to optical pulses, and the splay-phase synchronization, leading to quasi continuous wave optical output. Both states can be generated on demand in a single semiconductor laser. By varying the laser design and the biasing conditions, frequency- and amplitude-modulated combs can be generated on demand. Second, based on their identifed particular temporal characteristics, a novel technique to determine the sensitivity of semiconductor laser frequency combs to optical feedback, is presented. Results suggest, that amplitude-modulated semiconductor laser frequency combs are less sensitive to optical feedback than frequency-modulated semiconductor laser frequency combs. The developed insights are expected to elevate semiconductor laser frequency combs in current and future integrated photonic circuits in optical communications, where unavoidable optical feedback from downstream active and passive components deteriorates comb stability