Making use of the beam fanning effect in a BaTiO3 crystal, we propose two simple setups to perform the function of an optical image-combiner/OR-gate and an optical AND gate, respectively. The optical image combiner combines two patterns, mutually coherent or mutually incoherent, from two input channels into a single coherent one. Experimental results have shown that the response time of these devices ranges from 0.01 to 2.5 s. In the image-combiner/OR-gate device, three optical waves are involved. The first two carry the input signals into a 45-deg-cut BaTiO3 crystal; the third one brings the output out of the BaTiO3 crystal to the output plane. The AND-gate device, however, requires only two input beams.
