عنوان مقاله [English]
Plasmon-polaritons can confine an optical wave to a region with dimensions much smaller than the wavelength of the wave in free space. This increases the interaction of optical radiation with material that is suitable for sensing applications. For this reason, in this paper plasmon-polaritons in a nanolayer graphene at mid infrared spectral wavelengths are investigated. Owing to the large wavenumber of plasmon-polaritons in graphene relative to the wavenumber of an optical wave with the same frequency in free space, diffraction grating is used for exciting plasmon-polaritons in graphene. For investigating the effect of relaxation time on the plasmon-polaritons in graphene, relaxation time was varied from to and plasmon-polaritons in graphene were simulated by solving electromagnetic wave equation. The results show that while the variation of relaxation time does not affect the period of plasmon-polaritons in graphene, with the decrease of relaxation time confinement and intensity of the plasmon-polaritons in graphene decrease. In addition investigating the reflectance, transmittance and absorption spectra show that the intensity and the location of pick points in the reflection spectra are appropriate for qualitative determination of confinement, and quantitative determination of excitation wavelength of plasmon-polaritons in graphene.