  Coherent perfect absorption (CPA) is an interferometric effect that
guarantees full absorption in a lossy layer independently of its intrinsic
losses. To date, it has been observed only at a single wavelength or narrow
bandwidths, whereupon wavelength-dependent absorption can be ignored. Here we
produce CPA over a bandwidth of ~ 60 nm in a 2-um-thick polymer film with a
low-doping concentration of an organic laser dye. A planar cavity is designed
with a spectral `dip' to accommodate the dye resonant linewidth, and CPA is
thus achieved even at its absorption edges. This approach allows realizing
strong absorption in laser dyes - and resonant materials in general -
independently of the intrinsic absorption levels, with a at spectral profile
and without suffering absorption quenching due to high doping levels.
