Compact, affordable mid-IR lasers require the development of gain materials in waveguide form. We report on the high vacuum deposition of Cr:ZnS films with concentration ranging from 10 18 -10 20 dopants/cm 3 . At low concentrations, films display wellisolated absorption associated with substitutional Cr 2+ ions in the lattice. Spatial modulation of the dopant concentration suppresses the absorption associated with this substitution. Lateral crystallite sizes less than 30 nm are associated with the lowest substrate temperatures (<50 °C) used during deposition, and waveguide losses as low as 8dB/cm are observed. These materials are promising candidates as gain media for fabrication of waveguide mid-IR lasers. 4406-4414 (2015). 19. R. Swanepoel, "Determination of the Thickness and Optical-Constants of Amorphous-Silicon," J. Phys. E Sci.Instrum. 16(12), 1214-1222 (1983). 20. D. Minkov and R. Swanepoel, "Computerization of the Optical Characterization of a Thin Dielectric Film," Opt.Eng. 32(12), 3333-3337 (1993). 21. S. B. Mirov, V. V. Fedorov, K. Graham, I. S. Moskalev, I. T. Sorokina, E. Sorokin, V. Gapontsev, D. Gapontsev, V. V. Badikov, and V. Panyutin, "Diode and fibre pumped Cr 2+ :ZnS mid-infrared external cavity and microchip lasers," IEEE Proc. -Optoelectron. 150, 340-345 (2003).