Contents 1. Introduction
The inherent design flexibility of Quantum Cascade (QC) emitters has led to unique laser concepts that have revolutionized mid-infrared light sources [1]. Several innovative designs have focused on multi-wavelength QC devices [2]–[4]. One approach, while unsuccessful, attempted stacked optical transitions for a so-called “cascaded” QC laser [2]. Such a laser would be of interest for cascaded optical transitions that produce correlated photons, which have been demonstrated in other laser systems [5]. Here we report a dual-wavelength QC laser that shows simultaneous lasing from two cascaded optical transitions in its active regions.
