Lecture 8: Laser amplifiers

Three-level pumping
Under rapid 3 to 2 decay, the three-level system (assumed R
is independent of N)
R 1
R 2
R 1
2
21
In steady state, both the rate equations provide the same result
0 R N 2
21
N 2
W i
N 1
W i
As 32 is very short, level 3 retains a negligible steady-state
population. All of the atoms that are raised to it immediately
decay to level 2.
N 1
N 2
N a
98
98