▎ 摘　　要

Both transmission and reflection spectra were obtained from graphene microribbons on a SiC substrate, which resonantly coupled with terahertz light through plasmon excitation. An absorption spectrum was also derived from the transmission and reflection spectra. Absorption by the confined intraband plasmons reached 5-10%/layer, which is considerably larger than the wavelength-independent interband absorption of 2.3%/layer. The absorption was found to be larger when the microribbons/substrate sample was illuminated from the back surface than from the ribbon surface because of an interference effect at the surface. (C) 2016 The Japan Society of Applied Physics