Noncollinear mixing of radiation from CO2TEA lasers has been used to generate phase‐matched far‐infrared difference‐frequency radiation in GaAs. The wavelength of the far‐infrared radiation was tuned from [inverted lazy s] 70 &mgr;m to 2 mm in small steps by selecting the frequencies of the two CO2lasers by means of intracavity diffraction gratings. A theoretical analysis of the two‐dimensional phase matching is presented.