Steady-state laser oscillation:

(a) The He-Ne laser operates on several s --->p transitions in neon, including the 5s --->3P transition at 632.8 nm. Under the operating conditions of the laser, the fluorescence lifetimes of the upper and lower levels are approximately 100 ns and 10 ns respectively for this transition, and the Einstein-A coefficient is 10^7 s^-1. Taking the upper and lower laser levels to have equal degeneracies, determine whether or not it is possible, in principle, for continuous-wave laser oscillation to be observed on this transition.

(b) Repeat the calculation for the 3d^10 delta p 2^P_3/2 ---> 3d^9(delta)s^2 2^D_5/2 transition at 510 nm in the copper-vapour laser, given that the Einstein A coefficient is 2 x 10^6 s^-1 and the fluorescence lifetime of the lower laser level is approximately 10 us.