Communication Limits Due to Photon Detector Jitter

Detector jitter, the random delay from the time a photon is incident on a single-photon-counting detector (SPD) to the time an electrical pulse is produced in response to that photon, is characterized for a number of SPDs. The jitter is modeled as a weighted sum of Gaussians. The performance in detector jitter is measured by determining the capacity of a communications channel utilizing a given detector. It is observed that the loss, measured as the ratio of the signal power required to achieve a specified capacity in the presence of jitter to that in the absence of jitter, goes as the square of the normalized jitter standard deviation (the standard deviation of the jitter in slotwidths). The loss is small when the normalized jitter is less than one, and becomes significant beyond that point. This loss must be taken into account when evaluating detectors for very high throughput channels.