Inside a Laser
How Lasers Work
To understand how lasers work we have to first understand electrons. Electrons sit on different energy levels in the atom, and when an electron jumps down an energy level it emits a photon. Also when a photon hits the atom the atom simultaneously emits a daughter photon with the exact same energy and direction as the original photon. So when a material with excited electrons have 1 photon it can produce millions of identical photons.
Now when you add energy to the cavity by using a flash of light, a chemical reaction, or electrical energy (spark or constant current) you can excite the electrons. This causing them to move into a higher energy level. When photons spontaneously emit many are absorbed by the walls in the cavity. But some bounce off of the mirrors on each side. The photons that bounce off of the mirrors hit other exited atoms which creates more daughter photons.
There are two mirrors in the laser. One that reflects 100% of the photons off, and the other that reflect 95% of the photons off. The light ray that we call a laser is the 5% of photons that don't get reflected. This is what we call a laser! (refer to figure 4)
Now when you add energy to the cavity by using a flash of light, a chemical reaction, or electrical energy (spark or constant current) you can excite the electrons. This causing them to move into a higher energy level. When photons spontaneously emit many are absorbed by the walls in the cavity. But some bounce off of the mirrors on each side. The photons that bounce off of the mirrors hit other exited atoms which creates more daughter photons.
There are two mirrors in the laser. One that reflects 100% of the photons off, and the other that reflect 95% of the photons off. The light ray that we call a laser is the 5% of photons that don't get reflected. This is what we call a laser! (refer to figure 4)
Figure 4
In the diagram above you can see the process where photons are produced and reflected.
In the diagram above you can see the process where photons are produced and reflected.