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Fiber Propagation Dynamics

SPEC: G.652D COMPLIANCEOPTICAL REFRECTION V2.0
Precision Coefficient
FLOAT64_NATIVE
RANGE: 1.0 - 3.0
Velocity Factor (VF)
68.17%
Medium Velocity
204,358 km/s
Latency Overhead
0.005 ms/km
Real-Time Propagation Benchmarking
REFRACTIVE INDEX: n=1.467
VACUUM (n=1.0) FIBER CORE (n=1.467)REF: c (Vacuum)

100KM Path Latency (ms)

FIELD ADVISORY: G.652 VS G.657

While standard SMF-28 has an index of approx 1.467, bend-insensitive fiber (G.657) can have slight variations in the refractive profile. For precise OTDR validation, always verify the IOR (Index of Refraction) against the manufacturer's data sheet to prevent distance reporting errors.

v=c/nv = c / n
Speed is inversely proportional to the refractive index of the medium.
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Optical Propagation Theory

Why "n" Matters: The OTDR Calibration

An Optical Time-Domain Reflectometer (OTDR) measures the time it takes for a light pulse to bounce back from a fault. To convert that time into distance, the device needs to know exactly how fast light is moving in that specific batch of glass.

A mistake of just 0.005 in the refractive index can result in a 34-meter error over a 10km link. In urban maintenance, that's the difference between digging up the right manhole and a costly mistake.

Mathematical Foundation

The relationship is defined by the absolute refractive index:

  • Velocity (V) = c / n
  • Standard Silica Fiber (SMF): 1.467
  • Multi-mode Fiber (MMF): 1.472 - 1.485

Technical Standards & References

REF [IEC-60793]
IEC (2017)
Optical fibres - Part 1-22: Measurement methods and test procedures - Length measurement
“Defines the standard methodology for using Group Refractive Index in OTDR distance calculations.”
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REF [ITU-T G-Sup1]
ITU-T (2020)
Optical fibre and cable - Characteristics
“Compendium of material properties for single-mode and multi-mode optical transmission.”
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REF [CORNING-IOR]
Corning Optical Fiber (2018)
The Impact of Index of Refraction (IOR) on Fiber Length Measurement
“Technical white paper detailing environmental impacts on silica fiber propagation velocity.”
Mathematical models derived from standard engineering protocols. Not for human safety critical systems without redundant validation.

Related Engineering Resources

Partner in Accuracy

"You are our partner in accuracy. If you spot a discrepancy in calculations, a technical typo, or have a field insight to share, don't hesitate to reach out. Your expertise helps us maintain the highest standards of reliability."

Contributors are acknowledged in our technical updates.