I've been reading about how light is produced in both laser diodes (the most common types of lasers) and LED's.
The mechanism seems very similar if not exactly the same: one applies a potential difference through a semi-conductor material that emits light when the electrons recombine with holes in a p-n junction.
Thus I would have expected the broadness of the spectrum of both laser diodes and LED to be similar. However they aren't. Here's the spectrum of some LED's: https://upload.wikimedia.org/wikipedia/commons/f/f4/Red-YellowGreen-Blue_LED_spectra.png.
While the spectrum of a laser can be found there: http://ondax.com/wp-content/uploads/2011/01/chart.jpg or there: http://ledmuseum.candlepower.us/rlspec4.htm.
We can see that the spectrum of a laser diode is much narrower in terms of wavelengths than that of a LED's one. I'd appreciate if someone could tell me why it is so or any reference where I can read the reason.