Lasers- the avg power of the resulting laser pulse over a time interval

[exzacklyright]

Homework Statement

Suppose that total population inversion could be achieved in a ruby laser. If half of the electrons in E2 could then drop to E1 in 30 ns, what would be the avg power of the resulting laser pulse over this time interval? Assume that the ruby crystal is a cylinder 5.00cm long and 1.19cm in diameter and that on Al in every 1700 has been replaced by a Cr. Density of Al2O3 = 3.7g/cm^3. E2-E1=1.786eV

Homework Equations

h(bar)w = E2-E1

The Attempt at a Solution

I have no idea really. That eqn above is all my book gives. Somehow it's creating a situation where more electrons are in states of energy E2 than in state of energy E1.

 

[ehild]

Read this, to understand how a ruby laser works.

http://people.seas.harvard.edu/~jones/ap216/lectures/ls_2/ls2_u5/ls2_unit_5.html

In principle, you need the number of Chromium atoms in the ruby crystal to find the number of photons emitted in 30 ns.

ehild