Five-Stack Heterogeneous Terahertz Quantum Cascade Laser For Ultra-Broadband Emission

We present the design, fabrication and characterization of a heterogeneous terahertz quantum cascade laser consisting of five individual active regions emitting at different wavelengths. The combination of these five designs in a single structure leads to ultra-broadband emission covering 2.6 THz between 1.9-4.5 THz.