Optical Power - Power or Loss
Practically every measurement in fiber optics refers to optical power measured in dB. The power output of a transmitter or the input to receiver are "absolute" optical power measurements, that is, you measure the actual value of the power. Loss is a "relative" power measurement, the difference between the power coupled into a component like a cable, splice or a connector and the power that is transmitted through it.
This difference in power level before and after the component is what we call optical loss and defines the performance of a cable, connector, splice, etc. Take a minute and read about "dB," the measurement unit of power and loss in optical fiber measurements.
December 20, 2011