Hollow metallic waveguides for beam shaping THz QCL

We have realized a compact beam-shaping and collimating element for a double metal terahertz (THz) quantum cascade laser (QCL) emitting around 2.9 THz using directly integrated hollow metallic waveguides. Our approach allowed us to efficiently improve the beam profile with respect to the standard emission pattern observed out of a double metal QCL. The Gaussian-like mode profile emerging from the metallic waveguides also exhibited a remarkable degree of collimation. The other laser characteristics such as the total output power and maximal operational temperature were marginally affected.