Tailoring GaAs terahertz radiative properties with surface phonons polaritons

Absorption of visible and infrared radiation by gratings due to the resonant excitation of surface waves is a well-known phenomenon. In this paper, we study the resonant absorption of terahertz (THz) radiation due to the excitation of surface phonon polaritons on a grating ruled on a GaAs substrate. We report the design and fabrication of such a grating. Reflectivity measurements clearly show the excitation of surface phonon polariton. Numerical simulations indicate that the radiative properties depend critically on the surface profile. We finally discuss potential applications to THz thermal emission.