Broadband light absorption in graphene ribbons by canceling strong coupling at subwavelength scale

We theoretically investigate the broadband light absorption in the THz range by canceling the strong coupling in an array of graphene ribbons at subwavelength scale. A series of resonators with different absorption frequencies can achieve a broadband absorber, however, the suppression of absorption always accompanies since the mutual coupling between resonators cause the mode splitting. By adjusting the near- and far-field coupling between the plasmon resonances of the graphene ribbon array to the critical point, the absorption linewidth is broadened for almost one magnitude larger than that of individual graphene ribbon, to be similar to 1 THz. Our study provides not only insight understanding but also new approaches towards the broadband graphene absorber. (C) 2016 Optical Society of America