Dispersion in a broadband terahertz quantum cascade laser

We presentdispersion data of a broadband terahertzquantum cascade laser with a heterogeneous active region. The experimental method to extract the group velocitydispersion of the entirelaser cavity, including the contributions of the active region, the semiconductor material, and the waveguide relies on a time-domain spectroscopy system. The obtained group velocitydispersion curves exhibit oscillations with amplitudes up to 1  × 105 fs2/mm between 2.0 and 3.0  THz and strongly depend on the driving conditions of the laser. This indicates that the group velocitydispersion is mainly determined by the intersubband gain in the active region. The obtaineddispersion data are compared to adispersion model based on multiple Drude-Lorentz gain media yielding a significant correlation.

Source: Applied Physics Letters - December 1, 2016 Category: Physics Authors: Dominic Bachmann, Markus R ösch, Giacomo Scalari, Mattias Beck, Jérôme Faist, Karl Unterrainer and Juraj Darmo Source Type: research