▎ 摘　　要

The graphene ribbon waveguide with two short parallel, coupled coplanar strips is investigated. Because of the extreme destructive interference of the short strip resonators, an outstanding plasmonically induced transparency (PIT) window with a group time delay up to 0.28 ps is achieved in the mid-infrared region, with an excellent ultraslow-light feature. The PIT window is controlled by varying the coupling distance between resonators and is tuned dynamically by a small change in the chemical potential. Numerical results are confirmed using the coupled-mode theory (CMT). The planar structure will benefit the fabrication of plasmonic circuits for slow light and optical switching. (C) 2016 The Japan Society of Applied Physics