We report on the influence of a well-designed passband in the stop band of a suitably engineered self-assembled colloidal photonic crystal superlattice on the steady-state emission properties of infiltrated fluorophores. The photonic superlattice was built by convective self-assembly of slabs of silica spheres of two different sizes. Transmission experiments on the engineered photonic crystal structure show two stop bands with an effective passband in between. The presence of this passband results in a narrow spectral range of increased density of states for photon modes. This shows up as a decrease in the emission suppression (enhancement of the emission) in the narrow effective passband spectral region. These experiments indicate that the threshold for lasing can possibly be lowered by spectrally narrowing the emission of fluorophores infiltrated in suitably engineered self-assembled photonic crystal superlattices, and are therefore important towards the realization of efficient all-optical integrated circuits from functionalized photonic superlattices and heterostructures. (c) 2006 American Institute of Physics.