  In this paper, we study the excitation of guided resonances (GRs) in
photonic-crystal slabs based on point-defected aperiodically-ordered
supercells. With specific reference to perforated-slab structures and the
Ammann-Beenker octagonal lattice geometry, we carry out full-wave numerical
studies of the plane-wave responses and of the underlying modal structures,
which illustrate the representative effects induced by the introduction of
symmetry-preserving and symmetry-breaking defects. Our results demonstrate that
breaking the supercell mirror symmetries via the judicious introduction of
point-defects enables for the excitation of otherwise uncoupled GRs, with
control on the symmetry properties of their field distributions, thereby
constituting an attractive alternative to those GR-engineering approaches based
on the asymmetrization of the hole shape. In this framework,
aperiodically-ordered supercells seem to be inherently suited, in view of the
variety of inequivalent defect sites that they can offer.
