Coherent THz generation based on a novel dual-frequency III-V semiconductor laser

We demonstrate coherent THz emission based on the stable operation of a dual-frequency vertical-external-cavity surface-emitting laser. The laser operates on two Laguerre-Gauss transverse modes in a single-axis cavity, thanks to sub-wavelength thick metallic transverse mask deposit on the surface emitting semiconductor structure. A beat note at frequencies from 50 GHz to 3 THz has been demonstrated and coherent THz emission was demonstrated at 190 GHz by excitation of a uni-travelling-carrier photodiode emitter.