Estimating the Probability Density Function of the Detected Intensity of Optical Light Sources

Abstract

The most commonly used optical transmitters are semiconductor devices such as light-emitting diodes (I.liDs) and laser diodes. The ditlerence between LEDs and laser diodes is that LEDs produce incoherent light, while laser diodes produce coherent light. The intensity distribution ol light source is very important in many applications ol‘ optical libel‘ communications especially error rate calculations. We performed two experiments, in the first experiment we detected the intensity of Llil) sources for ditferent electrical bandwidths, and in the second experiment, the intensity of several laser source are detected for cases \\hen the sources have identical central frequencies and when the sources have a small shifl in the central frequency. Results show a Gamma probability density function (pdl) can give a very good approximation ofthe detected intensity of the incoherent light source while the laser intensity is approximated by its mean value when lrequency displacement is implemented.