What is a good dBm reading for fiber?

A good dBm reading for a passive single-mode fiber link typically falls between -10 dBm and -25 dBm at the receiver, depending on transmit power and run length. Readings outside that range — especially below -30 dBm — usually indicate a loss problem worth investigating.

Optical power meter readings tell you whether actual light arriving at the receiver matches what the link budget predicts. On a typical FTTx drop, total insertion loss from connector to connector runs 3–5 dB on single-mode fiber, factoring in fusion splices and connectors. If your D YEDEMC optical power meter shows a received signal weaker than your loss budget allows, the trace from an OTDR will tell you exactly where the loss is occurring.

• Normal received power range for passive optical links: -10 dBm to -25 dBm on single-mode fiber.
• Acceptable total insertion loss on a typical FTTx single-mode drop: 3–5 dB connector to connector.
• Acceptable fusion splice loss on single-mode fiber: ≤ 0.05 dB in practice; ≤ 0.02 dB is excellent.
• Flag for concern: any OTDR splice event showing greater than 0.2 dB loss warrants a re-splice.
• D YEDEMC optical power meter measurement range: -70 to +6 dBm across 8 wavelengths (850–1650nm).