Table of Contents:
- Four-Level Laser System
- Four-Level Pumping Analysis
- Fluorescent Quantum Efficiency
- Four-Level Population Inversion
- Three-Level Laser System
FOUR-LEVEL LASER SYSTEM
In a previous section, we discussed the basics of multi-level systems. Here, we will go more in depth with what is meant by a four-level system. As you might imagine, a four-level system is that you have 4 quantum levels that comprise the scheme of your laser. A gain medium may have other quantum levels (analogous to orbital levels if you are more familiar with chemistry), but a four level laser system means that the absorption, initial decay, and spontaneous and/or stimulated emission all occur within four levels. The diagram below shows how the laser scheme may look like.