  The positive effects of various perturbations introduced in a bidimensional
photonic-crystal patterned membrane on its integrated absorption are
investigated numerically and theoretically. Two phenomena responsible for the
enhanced absorption observed are identified: an increase of the spectral
density of modes, obtained thanks to folding mechanisms in the reciprocal
lattice, and a better coupling of the modes with the incident light. By
introducing a proper pseudodisordered pattern, we show that those two effects
can be exploited so as to overcome the integrated absorption obtained for an
optimized and single pattern unit cell photonic crystal.
