We design, fabricate and characterize the InAs(0.87)sb(0.13) film with cutoff wavelength of 4.6 mu m on InAs (1 00) substrate, which is widely used as active layer of the multilayer device architecture for mid-infrared device used for the monitoring of carbon monoxide at 4.6 lam. In order to accommodate the large lattice mismatch between the InAs0.87Sb0.13 epilayer and the InAs substrate, the InAs(0.92)sb(0.08) buffer layer was introduced. We acquired the complete absorption spectra and subsequently derived the basic parameters of InAs(0.87)sb(0.13) film and InAs(0.92)sb(0.08) buffer layer about absorption coefficient, optical energy band gap and the characteristic energy of Urbach edge from the Fourier transform infrared (FTIR) transmission spectra, which are very useful for modeling and simulation in the devices design. (C) 2015 Elsevier B.V. All rights reserved.