High-power surface emission from terahertz distributed feedback lasers with a dual-slit unit cell

We present a surface emitting distributed feedback terahertz laser resonator based on a dual-slit configuration. With the spacing of the slits as a parameter, the surface losses of the lasers can be chosen over a large range, while keeping slits narrow for optimum current injection. Quantum cascade devices based on a double metal waveguide showed slope efficiencies up to 40 mW/A and peak powers of more than 20 mW. The efficient radiation out-coupling does not depend on boundary conditions, and therefore would allow the application to large-area devices, making this an ideal resonator for high-power surface emission.