The aim of this chapter is to provide an utilitarian and succinct overview of the emission characteristics of lasers. Lasers included in this survey emit mostly in the ultraviolet–visible–near-infrared part of the spectrum and offer one, or more, of the following features:
Narrow linewidth emission
TEM00 beam profile
High pulsed powers, high average powers, or high continuous-wave (CW) powers
At this stage, it should be indicated that lasers that exhibit naturally a high degree of spectral coherence tend to be lasers that derive their emission from discrete atomic transitions. Examples of such coherent sources are found among the CW gas lasers, which also tend to emit laser beams ...