Beam and phase distributions of a terahertz quantum cascade wire laser

Abstract

We report on both measurements and simulations of the beam profile and wavefront of a single-mode, 3.5 THz quantum cascade wire laser, incorporating a lateral corrugated metal-metal waveguide, 3rd-order distributed feedback grating. The intrinsic wavefront was measured by using a Hartmann wavefront sensor (HWS) without any optical components between the laser and HWS. Both beam profile and wavefront were simulated using an antenna array model, but taking the non-uniform electric field distribution along the waveguide into account. The results show that the non-uniform distribution along the wire laser plays a crucial role in realizing a nearly single-lobed narrow beam. The measured wavefront is spherical and agrees well with the simulation.