Strange electric-optical unit (a.u.)

[Micko]

Hello to all,
I'm reading one article about LT (low temperature) GaAs MSM (metal-semiconductor-metal) photo switches that has application in ultrafast sampling.
Basically, there is one photoswitch in series with hold capacitor. Special test is performed which gives electro-optical signal depending on time. Problem is in the way how plot is given in the terms of units. On x-axis is time in ps, but on y-axis in signal given in a.u. I know that a.u.means atomic unit, but this is not it, it can't be. I cannot find any other meaning of a.u.
Do you know what this could mean?
Thanks

 

[f95toli]

a.u. can also mean arbitrary units.
I suspect they are measuring the signal using an instrument where they can't easily relate the absolute value of the signal to the reading; i.e. only the relative value of the signal is important.

This is quite common in experimental physics; in many experiments it is almost impossible to "calibrate" the instruments which is fine as long as one is only interested in how a signal changes over time.

 

[Claude Bile]

This is quite common in experimental physics; in many experiments it is almost impossible to "calibrate" the instruments which is fine as long as one is only interested in how a signal changes over time.

I wouldn't say so much as impossible as irrelevant in a linear system since the absolute readings scale with the power of your source anyway.

Claude.