Abstract We present a Fourier transform photoluminescence study of InAs/AlSb type II heterostructures, spanning the mid infrared 1 μm - 12 μm wavelength range. The investigated samples consist of single-, double-, and multi-quantum wells, grown on GaAs substrates by molecular beam epitaxy, with different buffer layer structures for strain accommodation. The photoluminescence intensity is found to be very sensitive to the detailed structure of the underlying buffer sequence. Calorimetric measurements of the absorbance at 500 mK shows the weak spatially indirect transitions superimposed onto the spatially direct absorbance. Very wide quantum wells (100 nm and 200 nm) exhibit spatially direct as well as spatially indirect pbotoluminescence. Polarization resolved photoluminescence of the spatially indirect transitions allow the contributions of the normal (AlSb on InAs) and the inverted (InAs on AlSb) interface to be separated.