taap.digitalnetwork engineering toolkit

How much loss does a 2 km fiber link have?

Answer
6.40 dB total · single-mode 1310 nm

A 2 km single-mode link at 1310 nm loses 0.700 dB in the fiber (0.350 dB/km). With 2 connector pairs, 4 fusion splices and a 3 dB margin, the total is 6.40 dB.

fiber-loss · adjust the values
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Loss breakdown

ItemValue
Fiber0.700 dB
Connectors (2 × 0.75 dB)1.50 dB
Splices (4 × 0.3 dB)1.20 dB
Margin3.00 dB
Total6.40 dB

Compare the total with the transceiver's power budget (Tx power minus Rx sensitivity). If less than 3 dB is left, check the connectors or use longer-reach optics.

More questions like this

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Frequently asked questions

1310 or 1550 nm?

1550 nm attenuates less (≈0.25 dB/km) and is used for long runs; 1310 nm (≈0.35 dB/km) is typical up to 10–20 km.