Influence of the facet type on the performance of terahertz quantum cascade lasers with double-metal waveguides

We investigate the influence of cleaved and dry chemically etched facets on the performance of terahertz quantum cascade lasers with double-metal waveguides.We theoretically show that the reflectivity and therefore also the mirror losses depend on the facet type.We fabricated devices employing both a cleaved and an etched facet, which show an asymmetric output characteristic.Furthermore, we compare the performance in terms of maximum operation temperature of lasers with each facet configuration.The results suggest that the devices are operated in a mirror loss dominated regime.