Far‐infrared generation by optical mixing and by stimulated Raman scattering via spin‐flip transitions is treated using the general formalism of coherent excitation of polaritons. Practical numerical examples for InSb are given. The result for the case of optical mixing agrees well with the experimental result of Nguyen and Bridges. The calculation also suggests that the far‐infrared output from a spin‐flip Raman laser should be easily observable.