We have fabricated two-dimensional photonic crystals for the mid-infrared spectral range. These photonic crystals are engineered in order to show optical modes in resonance with quantum dot intersublevel transitions. A novel fabrication technique was developed to obtain suspended membranes in a planar geometry. The membranes are 3 μm thick and the lattice periodicities vary between 3.5 μm to 6.5 μm. We show that the photonic crystals modes can be probed by the room temperature emissivity using a photomodulation technique. Bloch-modes of the photonic crystals are observed around 11 μm wavelength. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)