A tunable THz absorber consisting of an elliptical graphene disk array.

Abstract

Herein, we present an adjustable absorber consisting of a periodically patterned elliptical graphene disk array, which absorbs in the THz region. When a circularly polarized light beam illuminates this structure, its absorption spectrum displays two absorption peaks, which originate from the F-P resonance of the fundamental graphene edge plasmon mode along the major and minor axes of the elliptical graphene disk. The position of these two absorption peaks can be modulated by changing the Fermi level of graphene. Furthermore, both absorption bands can merge into one broadband by changing the length of the major and minor axes. The full width at half maximum (FWHM) of the broadband can reach up to 3.52 THz. In addition, by changing the incident elliptically polarized light, the peak ratio between the two absorption bands can also be tuned to convert the double-band absorption to single-band absorption.