Optical frequency combs in quantum dot fabry-perot lasers: Role of the spatial hole burning

The transmission of huge amount of data at Tbit/s rate in short distance optical interconnect has successfully employed quantum dot (QD) or quantum dash (QDash) multi-wavelength lasers (optical frequency combs) integrating one single section laser chip with the silicon photonics modulators [1]. The “comb” characteristics (i.e. self-phase locking of the lasing wavelengths separated by one cavity free spectral range) of single section QD and QDash lasers have been demonstrated in several experimental works [2-4], but the understanding of the fundamental physical effects behind the comb generation is still ongoing.