Four-Level Laser System: Why Less Energy?

[ScienceKitten]

I know this might sound basic to a lot of you but in school I've started taking lasers and laser mechanics in my physics course and so we reached the whole four-level system and three-level system lasers and I have a question..

Why do four-level systems require less energy than the third-level systems? As far as I know, electrons can go to higher energy levels (excited) if they have more power. So how would I send an electron from E₁ to E₄ with less pumping power than from E₁ to E₃ ?

Please try to keep the answer as simple as possible because English isn't my main language so I might have some difficulties with large words.

Thanks in advance!

 

[Greg Bernhardt]

Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?