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We investigate the cause of the insertion loss of our holographic switch by determining the relation between the diffraction efficiency and the hologram patterns generated by the control beams. According to the calculation the theoretical insertion loss is 7.4 dB with loss distribution of 0.03 dB under the conditions of a previous experiment. We find that incomplete storage of the interference pattern on the optically addressed spatial light modulator is the strongest factor determining the insertion loss.

We extended the scale of a previously reported holographic switch [Appl. Opt. 34, 8137 (1995)] in which each input is assigned to one of the control light sources to control a large-scale switch with low power. The average losses of the four inputs were 28, 33, 35, and 36 dB. The average cross-talk-to-signal ratio of one of the inputs was -16 dB. Key words: Holographic switching, optical interconnects, spatial light modulator, ferroelectric liquid crystal.

Simulating the positions of output beams under the assumption that a liquid-crystal display acts as a binary phase modulator reveals that the number of the outputs increases almost linearly with the square root of the number of pixels assigned to an input. This result is confirmed by experiments, and it is estimated that 1016 outputs can be obtained when the number of pixels is 700 X 700. Holographic switches with liquid-crystal displays are therefore suitable for large-scale switches. Key words: Holographic switching, liquid-crystal display, computer-generated hologram.