A dual-fiber link has one receive and one transmit, with one more optical fiber changing one direction; a single-fiber link puts transmit and receive on the same fiber, and uses different wavelengths in the two directions to distinguish signals. Structural differences determine that you cannot just pair two single-fiber modules - the transmitting and receiving wavelengths do not match, and neither end can receive the other. This is the biggest pitfall in single-fiber selection.

First, separate the transmission structures of single-fiber and double-fiber

The two ends of the dual-fiber module have the same wavelength. TX takes one fiber to the opposite end RX, and the directions are physically separated by the optical fiber, so two of the same model can be interconnected, for exampleSFP Gigabit single mode dual fiber 10KM optical moduleCan be used in pairs. There is a WDM filter structure inside the single-fiber module. One fiber runs two wavelengths, 1310nm and 1550nm, at the same time. Each direction only releases its own receiving wavelength. The hardware determines that it must find the "complementary" other end.

TX/RX wavelength determines A/B pairing

• The common pairing is that the A end transmits 1310nm and receives 1550nm, and the B end transmits 1550nm and receives 1310nm. The labels are written as TX1310/RX1550 and TX1550/RX1310;
• Only two pairs with opposite wavelengths can be connected. Two pairs with the same A end can never connect;
• Some manufacturers use -A/-B or paired wavelength segments (such as 1490/1310) to distinguish them. The naming is not uniform, and the wavelength on the specification page shall prevail;
• When multi-fiber core resources are tight, the same fiber can be staggered in multiple stages according to different wavelength segments, but the loss must be calculated segment by segment.

Which scenarios are suitable for replacing single fiber?

The value of a single fiber lies in saving half of the optical fiber: the existing monitoring pipe network only has one fiber, the point-to-point link fiber core is in short supply, and FTTH home access only has a single core. In these scenarios, the capacity can be expanded by replacing the single fiber combination. There are also mature options for the transceiver side in security transformation, such asGigabit single mode single fiber one optical one electrical fiber optic transceiverIt is also matched according to the A/B pairing principle, please refer toPhase III of "Safe City" video surveillance optical fiber transmission of a city's Public Security Bureaupair management experience. Equipment rooms with sufficient dual-fiber resources do not need to pay higher costs for single fibers. You can choose each section separately; please ask EB-LINK technical support for assistance in verifying the paired plan and wavelength.