Analysis of light-emission processes in light-emitting diodes and semiconductor lasers

Abstract

We present a laboratory experiment to show the current - voltage (I - V), light output - voltage (L - V) and light output - current (L - I) characteristics of light-emitting diodes (LEDs) and semiconductor laser (SLs). The experiment allows us to compare the processes of light emission in LEDs and lasers below the threshold (spontaneous emission) and above it (stimulated emission). We establish unambiguously the analogies of the characteristics of LED emission in comparison with laser emission, when this occurs in the regime of spontaneous emission. We also determine the differences between LED and laser operation (when this occurs in the regime of stimulated emission) in a different way than that usually found in textbooks.