title: Quantum cascade laser combs: effects of modulation and dispersion.
abstract: Frequency comb formation in quantum cascade lasers is studied theoretically using a Maxwell-Bloch formalism based on a modal decomposition, where dispersion is considered. In the mid-infrared, comb formation persists in the presence of weak cavity dispersion (500 fs2mm-1) but disappears when much larger values are used (30'000 fs2mm-1). Active modulation at the round-trip frequency is found to induce mode-locking in THz devices, where the upper state lifetime is in the tens of picoseconds. Our results show that mode-locking based on four-wave mixing in broadband gain, low dispersion cavities is the most promising way of achieving broadband quantum cascade laser frequency combs.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Villares
authors.forename: Jérôme
authors.initials: J
authors.lastname: Faist