A bidirectional multichannel photonic switching architecture based on the ALOHA multiuser scheme is presented and analyzed. An implementation of the broadcasting hardware, which uses free-space digital optics and fiber-bundle arrays, is described. The advantages and disadvantages of such an implementation are outlined, and the throughput and delay performance of it are analyzed and compared to other architectures. Our investigation shows that the switching capacity of such an architecture grows at least linearly in the number of channels.