Chapter 7, Problem 7.7QAP

Interpretation Introduction

Interpretation:

The reason for the four level laser system to be more efficient than the three-level type needs to be explained.

Concept introduction:

In a normal system there are more atoms in the low energy states as compared to the number of atoms in the high energy states. Population inversion is said to occur when there are more atoms in the high energy states than in the low energy states.