The fusion splicer relies on image fitting to estimate loss. It does not know whether the two optical fibers are of the same material. When two fibers with a large difference in mold field diameter are connected, the difference between the screen display value and the actual measured value can be more than 0.1 dB. This kind of deviation cannot be solved by adjusting the gear.

Mode field diameter mismatch brings directivity

The mode field diameter of conventional G.652D single mode at 1310 nm is about 8.2 to 9.5 μm, and there will be differences between different manufacturers and different batches. When the same section is measured from terminal A and measured from terminal B, it is not uncommon for one to be positive and the other to be negative. The one-way curve even has an upward gain step. This is the physical reason why acceptance requires the averaging of measurements in both directions, not the form of the process.

The test wavelength must be aligned with the equipment

For single-mode links, 1310 nm is used to view the near-end and overall loss, and 1550 nm is used to view bend-sensitive points. The latter is more sensitive to macrobends, and the fiber is most easily exposed here if it is too tight. Multi-mode OM3 and OM4 use the 850 nm window, and the judgment thresholds and test methods cannot be applied to the single-mode ones. If used on the device sideSFP+ 10G single-mode dual-fiber 10km optical module, its working wavelength determines that the acceptance must cover this wavelength at least once; long-distance scenarios also need to be checkedSFP 2.5G single mode dual fiber 80KM optical moduleA type of dispersion and power budget, qualified loss does not mean qualified bit error.

Three on-site avoidance practices

• The same batch of optical cables is terminated with the same batch of pigtails. When splicing in mixed batches, the splicing points must be marked separately, and the acceptance form must be listed in one line.
• Multimode and single-mode are not compared in the same curve, and the fiber mode and refractive index settings of the instrument are also changed along with the fiber core.
• When the materials of the old fiber and the new fiber are unknown in the renovation project, a test jump and a two-way test are performed first, and then the acceptance threshold is determined.

Confirming that the materials are consistent first, and then discussing fine-tuning of parameters can avoid most disputes over mismatched readings. If you need to check the matching of fiber batch and module wavelength, please contact Wolflight technical support 0755-83179002.