explain LASERS

Question

explain LASERS

anonymous · Answer

LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. In a lasing material, there are two energy levels of interest, and there will be electrons distributed among these. At any time, an electron may fall from the higher level to the lower level, releasing a photon characteristic of this energy difference, with some random phase.
$----*----$
                   |
                   |                 /////\->  Photon
                   v
$---------$

This is called spontaneous emission. If this photon interacts with another electron in the higher level, it will cause the electron to fall to the lower level, again emitting a photon characteristic of this energy difference, and it will have the SAME phase as the incident photon as well as the original incident photon.
               $----*----$
                                  |
/////\->                   |                  //////-> Incident Photon
                                 v                  //////-> Emitted photon
              $---------$
This is called stimulated emission, and is the process by which a laser works. Lasers will also pump lots of energy into the material to make sure there are lots of electrons in the higher level, which can then be stimulated into emission.