Question

3) (15 points) In class we analyzed a four level laser system in detail. In this proble, we will try to understand a three level laser. Let's consider a quantum system with three discretae states, 1), 12), and |3). Assume that there is a pumping process that causes transitions between states |1) and l3) at a rate Wp. The laser transition involves the two lower states. a) Write the rate equations for the number of atoms in each state N, N2, and N3. Please use a notation consistent with what we used in class. b) Find the steady state population difference on the laser transition by solving the rate equations for N2 and N3 and using the conservation equation: Ni + M2 +M-N c) Plot the steady state population difference as a function of the pumping rate, W. What are the key differences when compared with a four level laser?

Note: The notation mentioned above is gamma for losses to different levels, and W_p for pumping from one level to another.

Answer 1

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