Resonance diffraction of THz HCN laser radiation on a semiconductor (InSb) grating is studied both experimentally and theoretically. The specular reflectivity suppression due to the resonance excitation of the THz surface plasmon-polariton is observed on a pure semiconductor grating and on semiconductor gratings covered with a thin striped layer of the residual photoresist. Presence of a thin dielectric layer on the grating surface leads to the shift and widening of the plasmon-polariton resonance. A simple analytical theory of the resonance diffraction on a shallow grating covered with a dielectric layer is presented. Its results are in a good accordance with the experimental data. Analytical expressions for the resonance shift and broadening can be useful for sensing data interpretation.
@article{arxiv.1305.1785,
title = {Surface plasmon-polariton resonance at diffraction of THz radiation on semiconductor gratings},
author = {I. S. Spevak and M. Tymchenko and V. K. Gavrikov and V. M. Shulga and J. Feng and H. B. Sun and Yu. E. Kamenev and A. V. Kats},
journal= {arXiv preprint arXiv:1305.1785},
year = {2013}
}