1490 fiber optic cable per kilometer

The typical attenuation of singlemode fiber at 1490 nm is approximately 0.2–0.5 dB per kilometer, with only a marginal difference compared to 1550 nm.Attenuation CharacteristicsFor singlemode optical fiber, the attenuation at 1490 nm is very close to that at 1550 nm, with a typical difference of about 0.02 dB/km . This means that over a standard PON fiber length of 10 km, the total difference in loss between 1490 nm and 1550 nm is minimal, around 0.2–0.3 dB, which is usually negligible for most network designs . The primary contributors to total link loss remain splices, connectors, and splitters, which are largely independent of wavelength.Typical Loss ValuesSinglemode fiber (1310–1550 nm range): 0.4–0.5 dB/km for outside plant installations .1490 nm in PONs: Slightly higher than 1550 nm by ~0.02 dB/km, effectively within the same range of 0.4–0.5 dB/km .Multimode fiber: Higher losses, e.g., 3 dB/km at 850 nm and 1 dB/km at 1300 nm, but 1490 nm is typically used in singlemode PON deployments .Practical ImplicationsNetwork Design: When calculating a loss budget for a PON, the 1490 nm wavelength can be treated similarly to 1550 nm for most practical purposes, as the difference is minor .Testing: OTDRs, light sources, and power meters can measure 1490 nm attenuation to verify fiber performance before equipment installation .Critical Scenarios: The small difference in attenuation becomes relevant only if the overall system loss budget is extremely tight, e.g., less than 30 dB, or if measurement uncertainty is very low . In summary, 1490 nm fiber optic signals experience very low attenuation, typically around 0.4–0.5 dB/km, and the difference from 1550 nm is negligible for standard PON distances, making it suitable for downstream data transmission in fiber-to-the-home networks .