If we consider two laser beams with identical 3 level energy level schemes except that the metastable state for one has a lifetime of 1μs and the other, 100μs. Which will give the brighter (more intense) beam? I gather that, since all things are identical up to the metastable state, the number of excited atoms in the energy level before the metastable state will be the same for both lasers(Is this correct, or is it a matter of probability?). From this excited state, they will spontaneously decay (stimulated emission unlikely here because of short lived state - please correct me if i am wrong) to the metastable state. Which will then give a brighter beam given the lifetimes above? Many thanks.