For example, Scully and colleagues were the first to make lasers oscillate without population inversion and have extended the coherent Raman spectroscopy techniques to detect anthrax type endospores.
32.
By suitable design of the layer thicknesses it is possible to engineer a population inversion between two subbands in the system which is required in order to achieve laser emission.
33.
This increases the overlap and hence W _ { 32 } which reduces the population inversion, but it increases the strength of the radiative transition and therefore the gain.
34.
In 1955, Prokhorov and Basov suggested optical pumping of a multi-level system as a method for obtaining the population inversion, later a main method of laser pumping.
35.
A fundamental characteristic of lasing, like the population inversion, is not actually possible in a two-level system and therefore a two level-laser is not possible.
36.
The special condition N _ 2 > N _ 1 is known as a population inversion, a rather unusual condition that must be effected in the gain medium of a laser.
37.
Unlike the usual side-pumping method, the light from a mercury arc lamp was pumped into the end of a very small rod, to achieve the necessary population inversion.
38.
Gas or gaseous mixtures that may lead to the formation of these molecules is a quasi-ideal laser medium since the population inversion is directly obtained when the excimer is formed.
39.
Collisional energy transfer between the nitrogen and the carbon dioxide molecule causes vibrational excitation of the carbon dioxide, with sufficient efficiency to lead to the desired population inversion necessary for laser operation.
40.
Once the plates are flashed and have settled into a population inversion, a small signal from a separate laser is fed into the optical lines, stimulating the emission in the plates.
