Bit error rate of optical logic: fan-in, threshold, and contrast

Bit error rates are calculated in the presence of shot noise for threshold optical logic devices that employ direct detection and intensity modulation. The device parameters considered are fan-in, contrast ratio, and light output. With given values for these parameters, the paper derives expressions for the device thresholds that generate the optimal bit error rates. In addition, it examines the fundamental quantum limit on reliability. Finally, the paper finds a bound on the device reliability that is sufficient to guarantee correct system operation with high probability.