The alloy semiconductor Hg 1− x Cd x Te has widespread use in modern infrared detection equipment. By adjusting the ratio of Hg to Cd, the energy gap can be tailored to any desired value between 0 eV ( x = 0.17) to 1.4 eV ( x = 1.0). For values of x near 0.2 the electron effective mass is small, giving rise to a large spin-level splitting factor, or ɡ-value. We have examined two nonlinear optical effects which depend upon the high ɡ-value found in small gap Hg 1− x Cd x Te. These are the spin-flip Raman laser and 4-photon mixing. In each case we employ CO 2 lasers as the input source. In order to achieve resonant enhancement, we adjust the energy gap so that the absorption edge at the temperature of operation, 4 K, is near 10 μm; the required composition is Hg 0.77Cd 0.23Te. During operation as a spin-flip Raman laser, we observe 1st Stokes, 2nd Stokes and anti-Stokes signals, with a basic tunability of 3.8 cm −1/kG for the 1st Stokes radiation. In the 4-photon mixing mode, we see resonant production of an output signal at frequency ω 4 = 2ω 2 − ω 1, where ω 2 and ω 1 are the frequencies of the two CO 2 pump lasers. We also observe under some conditions 6 photon mixing, i.e. ω 6 = 3ω 2 − 2ω 1.