Why is laser light special?

1 Answer
Sep 10, 2015

Laser light is not only monochromatic (only one wavelength, for example red) but also highly coherent.


You can imagine that the process of formation of laser light is similar to the formation of normal light where electrons of excited atoms undergo transitions emitting photons.
The emitted photons, in normal light such as the one from a normal light bulb or the Sun, come from different transitions at different times so are quite randomly distributed in wavelength and phase (they oscillates differently).

In laser light the radiation is emitted when electrons undergo the same transition all at the same moment (stimulated emission). This gives you radiation of waves all identical and in phase!