Multi-stack quantum cascade lasers

We demonstrate a double-waveguide quantum cascade laser (QCL) consisting of two full broadband QCLs vertically integrated into a single monolithic device. Up to 1.1W peak power at room temperature is obtained for this record thick QCL. Coupling between the two laser waveguides is minimized to reduce gain competition. Simultaneous lasing on Fabry-Perot modes separated by as much as 360 cm
^-1
is obtained. This design opens the route to high-power ultra-broadband mid-infrared sources.