We present measurements and a numerical modeling that elucidate the role of surface plasmons in the resonant transmission of a subwavelength slit in a conducting material. By using THz time domain spectroscopy, we determine the Fabry–Pérot transmission resonances for a single slit formed from a wafer of a semiconductor with a surface plasma frequency in the THz frequency range. We measure large redshifts in the resonant frequencies close to the surface plasma frequency, which are 50% lower than the resonance frequencies expected well below the surface plasma frequency. This is an effect attributed to the coupling of plasmons on the adjacent surfaces of the slit.

dx.doi.org/10.1103/physrevb.77.113411
Phys. Rev. B

Isaac, T.H, Gómez Rivas, J, Sambles, J.R, Barnes, W.L, & Hendry, E. (2008). Surface plasmon mediated transmission of subwavelength slits at THz frequencies. Phys. Rev. B, 77(Article number: 113411), 1–4. doi:10.1103/physrevb.77.113411