It is not uncommon for a return loss meter to read several dB off for the same jumper. Before interpretation, first confirm whether the return loss of a single point or the entire optical return loss is measured, then check the end face, and finally suspect the device itself.

The reading direction is opposite to the insertion loss

Return loss is the ratio of reflected light to incident light. The larger the value, the better. It is exactly opposite to the judgment direction of insertion loss. This is the most common misunderstanding. The 50 dB and 60 dB in the specifications correspond to different end-face processes: UPC polishing usually uses 50 dB as the judgment threshold, while APC relies on the end-face inclination to deflect the reflected light away from the fiber core, and the threshold is generally higher. If the reading on a single-mode long-distance link is only in the 40s, reflection back to the laser will cause power fluctuations and noise increases. The higher the rate, the more obvious the cost.

Single point return loss and ORL are not the same thing

What is measured on each connector is called single-point return loss, and the total amount after all reflections are superimposed on the entire link is called optical return loss ORL. In a link with many segments, there may be situations where all single points are qualified but the ORL is too small. The interpretation must be recorded by segment.LC-LC single mode dual core jumper and LC-SC single mode dual core jumperWhen transferred through an adapter, the transfer point itself is a reflection source. Point-by-point troubleshooting is more effective than overall retesting. Campus wiring projects can be comparedCampus network and FTTH integrated cabling solutionThe endpoint recording method.

Troubleshooting order for low readings

• Clean the end face and test port first. Most low temperatures come from oil dirt and dust.
• Use magnification to check for scratches and residual glue. If the end face geometry is defective, treat it as scrap.
• Make sure that the reference line has been reset to zero and that the adapter is in good condition. Do not include fixture problems in the DUT.
• The same device is plugged and unplugged multiple times and the reading range is taken. A large dispersion indicates that the ferrule or sleeve is worn.

It is recommended that the test wavelength, end face type, instrument and fixture number be specified in the report so that the readings can be reproduced. EB-LINK performs return loss testing on passive components before leaving the factory and retains end-face images. The determination threshold can be confirmed by calling 0755-83179002.