Experimental Evaluation of an Optical Time Division Demultiplexer for Twenty-four Channels

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Abstract
Experimental techniques for optical demultiplexing by use of sinusoidal polarization switches were evaluated. For this purpose the terminals of a twenty-four-channel optical PCM system were simulated by two channels separated in time by 124th the pulse period. The complete twenty-four PCM channels would have an information rate of 6.7 Gbit/sec. The measured values of cross talk in the demultiplexer were −13 dB and −9 dB for the two channels used in the simulated system. The major contributions to the cross talk were (1) intrinsic cross talk due to the use of a sine wave rather than a square wave for polarization switching (−19.6 dB and −13.1 dB); (2) light leakage in the demultiplexer crystals due to rf heating that gives rise to a nonuniform birefringence (−19 dB, both channels); and (3) misadjustment of the demultiplexer.