I am aware of crystals being energised with internal photoelectric effect, and then, somehow they are provoked to release the energy at once? The last part is what i don’t understand. How can a photon force emission of other photons? Or am i getting this wrong entirely?
In: 0
First, it doesn’t have to be a crystal. There are gas and liquid medium lasers. The important part is that the medium can have many excited electron states.
Think of the electrons like balls stacked in a pyramid. The ones on the bottom are most stable, they’re sitting on the ground (state). But in this example, no electrons can be put outside of the pyramid’s footprint. So you start stacking them. So you have a few less electrons above. And a few above that. It’s all still stable because there’s nowhere else for them to go. If they are given a bit of energy, they jump up a level, but then there IS space to fall down. So they do.
Lasers manipulate their medium in such a way, that the pyramid briefly (or continuously attemps to) inverts. Suddenly you have a lot of electrons on top that want to fall down.
Of course here the analogy breaks down a bit, because a physical pyramid of balls would immediately collapse. But electrons can have a delay. Still, the slightest nudge will bring it down. Interestingly, when a passing photon does so, the emitted photons aren’t random. They’re going to be closely matching the trigger photon. That’s why lasers emit a beam of (nearly) monochromatic light.
Latest Answers