Why are the Fermi levels in a semiconductor laser that is being pumped with external energy called “quasi-Fermi levels”?  Describe the characteristics of the light from a semiconductor laser diode as...

Why are the Fermi levels in a semiconductor laser that is being pumped with

external energy called “quasi-Fermi levels”?

 Describe the characteristics of the light from a semiconductor laser diode as

compared to those of a semiconductor LED.