Optical pumping is a method of creating a population inversion in a substance by exposure to electromagnetic radiation of a higher frequency than the frequency of a quantum inversion transition. This method, which allows shifting electrons in atoms from one magnetic sublevel to another, formed the basis for creating a quantum light generator - a laser .
Content
- 1 Theory
- 2 notes
- 3 See also
- 4 References
Theory
The method was discovered in 1950 by Alfred Castler , when a beam of light of the appropriate frequency raises atoms or molecules to a higher energy level, while not occupying all sublevels. It follows from this that during the reverse transitions of atoms to the ground state, the light propagates unevenly in different directions and is partially polarized in each direction. If the electromagnetic field applied to the raised atoms has the photon energy necessary to induce transitions between occupied and unoccupied sublevels and the emitted light changes both the polarization and the spatial distribution, this change indicates that the radio frequency is in resonance with the energy difference. Castlerβs optical pumping method has become a means of pinpointing the location of sublevels of ascending atomic states.
It is believed that during optical pumping, the atom is oriented toward level, but due to the cyclical nature of this process, the bound electron is actually subjected to repeated excitation and decay between sublevels of the upper and lower states. Laser polarization and pump frequency determine which sublevels oriented laser.
Notes
In practice, completely coherent optical pumping may not occur due to an increase in the power of the transition line width and undesirable effects, such as the capture of an ultrathin structure and the capture of radiation. Therefore, the orientation of an atom in a more general case depends on the frequency, intensity, polarization, spectral width of the laser strip , the line width, and the probability of transformation of the absorbing transition.
See also
Links
- Alfred Castler
- Stimulated emission