Multichannel Bragg cells are important components in many two-dimensional optical information processing systems. Multichannel Bragg cell design principles are discussed for both multichannel deflectors and modulators. Particular emphasis is placed on minimization of acoustic and electrical crosstalk and thermal effects through the use of acoustically anisotropic materials, rf stripline techniques, and high thermal conductivity materials. The use of a self-collimating shear mode in gallium phosphide (GaP) is found to substantially reduce acoustic crosstalk from that found in the commonly used tellurium dioxide cells. The use of stripline transmission lines substantially reduces electrical crosstalk over that obtained using the more conventional microstrip techniques. The performance is described of three different GaP multichannel Bragg cell deflectors and a GaP multichannel Bragg cell modulator designed using the principles Bragg cell deflectors and a GaP multichannel Bragg cell modulator designed using the principles outlined in this paper. Optical processing systems using multichannel Bragg cells for phased array antenna signal processing, multichannel rf spectrum analysis, and digital optical computing are discussed.