6.5
Special Lasers
Some lasers are based on different physical principles than the "standard"
lasers that were described so far.
The non standard features can be:
-
The pump energy is of special form
such as in Free
Electron laser (FEL).
-
The wavelength is so special such as
x-ray
laser.
-
The active medium takes a special form
as in fiber laser.
There is a lot of research activity in the last few years on:
-
Laser Without Inversion (LWI)
- in which lasing action can occur in a special case without achieving
population inversion.
Atom laser
- which is related to Bose Einstein
Condensation (BEC) at very low temperatures.