It is measured by comparing the power of the input signal to the amount reflected. But unlike insertion loss, higher return loss values are better — if no signal reflects back, there would be an. What you are measuring is the loss of the splitter due to the split ratio, excess loss from the manufacturing process used to make the splitter and the input and output connectors. To test the loss to. Scientifically, optical return loss (ORL) is the inverse of reflectance, and has the opposite sign, e. -50dB reflectance is 50dB return loss. • In fiber optic cabling systems, excess insertion loss can be caused by inferior-quality components or improper installation, such as contaminated fiber end faces, connector misalignments, or exceeding the fiber bend radius.