We report lattice constants, pseudobinary phase diagrams, crystal growth, and optical properties of the chalcopyrite CdGe(As1−xPx)2and AgGa(Se1−xSx)2solid solutions. The type‐II phase‐matching angle for frequency doubling of 10.6‐&mgr;m radiation has been measured for CdGe(As1−xPx)2crystals withx=0, 0.13, and 0.19. On the basis of the results, it is estimated that 90° phase matching would be obtained forx∼0.3.