Calculation Example: The optical power at the output of a fiber optic cable is given by the formula Po = P * e^ (-AL) - C - S, where P is the optical power at the input of the fiber, L is the length of the fiber, A is the attenuation coefficient of the fiber, C is the connector. Calculation Example: The optical power at the output of a fiber optic cable is given by the formula Po = P * e^ (-AL) - C - S, where P is the optical power at the input of the fiber, L is the length of the fiber, A is the attenuation coefficient of the fiber, C is the connector. While optical power meters are the primary power measurement instrument, optical loss test sets (OLTSs) and optical time domain reflectometers (OTDRs) also measure power in testing loss. TIA standard test FOTP-95 covers the measurement of optical power. Optical power is based on the heating power. Whenever tests are performed on fiber optic networks, the results are displayed on a power meter, OLTS or OTDR readout in units of “dB. ” Optical loss is measured in “dB” which is a relative measurement, while absolute optical power is measured in “dBm,” which is dB relative to 1mw optical power. Optical power is a critical parameter in optical communications, referring to the amount of optical energy transmitted through a fiber optic cable. One of the greatest advantages is its bandwidth. The light is a form of carrier wave that is modulated to carry information.