Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Institut für Physik

Institutskolloquium: Prof. Dr. Jérôme Faist (Institut für Quantenelektronik, ETH Zürich) spricht zum Thema "Quantum cascade laser frequency combs: physics and applications".

Abstract

The quantum cascade laser has recently been shown to operate as an optical frequency comb in both the mid-infrared and terahertz frequency range. We recently demonstrated a comb device delivering 1 watt of optical power over a bandwidth of more than 100cm^-1 at 8µm wavelength. While the general origin of the comb formation in these devices is relatively well understood, the precise nature of the comb state and especially the relative phases of the modes are still under debate.

After an introduction on these devices and their applications for dual-comb spectroscopy, we report on new experiments pointing to the existence of a very special state of the comb, where the instantaneous frequency chirps linearly time over the length of a cavity round-trip period.