Optical data signals are comprised of very short bursts of light, or optical pulses. When we transmit optical pulses through fiber, they broaden. This means that they become longer in duration as they travel through the fiber. If the fiber is long enough, this broadening causes the pulses to overlap and interfere with each other, which impacts the receiver’s ability to resolve the transmitted data, resulting in bit errors. This pulse broadening is due to a phenomenon called dispersion and limits the transmission bandwidth and distance. Single-mode and multi-mode fiber are each dominated by different types of dispersion.

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