Broadband Tunable THz Absorption with Singular Graphene Metasurfaces

By
exploiting singular spatial modulations of the graphene conductivity,
we design a broadband, tunable THz absorber whose efficiency approaches
the theoretical upper bound for a wide absorption band with a fractional
bandwidth of 185%. Strong field enhancement is exhibited by the modes
of this extended structure, which is able to excite a wealth of high-order
surface plasmons, enabling deeply subwavelength focusing of incident
THz radiation. Previous studies have shown that the conductivity can
be modulated at GHz frequencies, which might lead to the development
of efficient high-speed broadband switching by an atomically thin
layer.