The unit "a.u." commonly refers to "arbitrary units," particularly in the context of electromagnetic field measurements where it represents |E|^2. This designation indicates that the graphs display relative values without a specific scale. In scientific publications, such as those in the Physical Review journals, the use of "a.u." is discouraged in favor of clearer terminology like "arb. units" to prevent confusion with the Astronomical Unit, a measure of distance equivalent to approximately 1.09 x 10^9 meters.
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Are you sure that you have that right? a.u. usually refers to the Astronomical Unit, which is a measure of distance (I can't remember the exact conversion factor, but I'm sure its of the order of 109m).El Flea said:Does anyone knows what this unit "a.u" means? I found it on many graphs, where "a.u" represents the unit of |E|^2 (E represents electromagnetic field). How do I convert "a.u" to SI unit?
Well I never knew that! You learn something new every day, thanks jtbell.jtbell said:I suspect it means "arbitrary unit", that is, no particular unit at all. In this case those graphs are intended to show only the relative values of E^2 at different points on the graph, without regard for the overall scale.