Optical absorption edges of mixed AgClxBr1−x(0≤x≤1) crystals and polycrystalline fibers were investigated as a function of composition. Both visible edge, resulting from electronic transitions, and infrared edge due to multiphonon processes behave as the one‐mode (amalgamation) type of mixed crystals, shifting continuously with composition. Quantitative expressions were used to discuss the results. Polycrystalline extruded fibers preserve this spectral window of silver‐halide crystals, except for slight deviations which are explained by the small‐grain structure of the fibers.