Why two level laser is not preferable.justify your answer
Answers
Answer:
Population inversion is a necessary step in the workings of a standard model. In science this phenomenon of population inversion occurs when a system exists in a state in which more members of the system are in higher excited states than in lower unexcited energy states. It is called an inversion because in many familiar prevalent physical system this is not the usual case. Because the probalities for raising an electron to the upper level and inducing the decay of electrons to lower level known as population inversion are exactly the same , so optical pumping will at most only achieve equal population of a two level system. In simple words, when both levels are equally populated,the no of electrons going up and down will be same and so the most important ingredient population inversion can not be achieved in case of two levels. The only way out is to use a third METASTABLE STATE to solve the problem.
Answer:
we can't get population inversions of 2 level Laser no matter how much we pump it to the ground level