1.2.Common index
1.2.1.Insertion loss
insertion loss is the loss of signal power resulting from the insertion of a device in a transmission line or optical fiber and is usually expressed in decibels (dB).
The insertion loss of PLC Splitter is: IL=-10lg Pout/Pin. Pout is the optical power of output power, and Pin is the optical power of input power.

1.2.2.Return loss
Return loss is the loss of power in the signal returned/reflected by a discontinuity in a transmission line or optical fiber. This discontinuity can be a mismatch with the terminating load or with a device inserted in the line. It is usually expressed as a ratio in decibels (dB).
The return loss of PLC Splitter is RL=-10lgPril/Pin. Pril is the optical power, which returns from the device or the system to the input port of PLC Splitter and Pin is the optical power of input power.

1.2.3.Excess loss
Excess loss of PLC Splitter is the optical power loss of the total power of all output ports and that of all input ports and is usually expressed in decibels (dB).
Excess loss represents the quality of manufacturing technology. The lower it is, the better the manufacturing craft is.

1.2.4.Loss Uniformity
Uniformity of insertion loss between ports: the difference value of max. Insertion loss and min. Insertion loss.
Uniformity of insertion loss between wavelengths: for the same port, but different wavelengths, the difference value of max. Insertion loss and min. Insertion loss.

1.2.5.Directivity
Directivity is the ratio of the optical power launched into an input port to the optical power returning to any other input port.