Linear frequency-doubling in dual Mid-IR-wavelength quantum cascade laser active region

In this paper we have proposed a novel quantum cascade laser active region design to obtain a dual-mid-IR-wavelength laser which is capable of frequency-doubling (13.77-6.88 μm) without utilizing nonlinear processes in two coupled shallow and deep quantum well structures. Optimized design of the active region leads to higher dipole matrix elements and thus higher laser performances. This method can be used to design laser structures with different frequency ratios.