Analyze dispersion coefficient shifts across operating wavelengths instantly. Measure pulse broadening, bit period, and margins. Build stronger optical designs with clear results and exports.
Large screens use 3 columns, smaller screens use 2, and mobiles use 1.
| Scenario | Length (km) | λ op (nm) | Δλ source (nm) | Δλ chirp (nm) | D ref ps/(nm·km) | Slope ps/(nm²·km) | Bit rate (Gbps) | Total dispersion (ps) |
|---|---|---|---|---|---|---|---|---|
| Metro single-mode link | 25 | 1550 | 0.05 | 0.01 | 17.00 | 0.058 | 2.5 | 25.50 |
| Regional dense optical span | 80 | 1550 | 0.10 | 0.03 | 17.00 | 0.058 | 10 | 176.80 |
| 1310 nm low-dispersion route | 40 | 1310 | 1.00 | 0.00 | 0.50 | 0.090 | 2.5 | 20.00 |
These rows are illustrative engineering examples for validation and training.
1) Effective spectral width
Δλeff = Δλsource + Δλchirp
2) Wavelength-adjusted dispersion coefficient
D(λ) = Dref + S × (λop − λref)
3) Total chromatic dispersion or pulse broadening
ΔT = |D(λ)| × Δλeff × L
4) Bit period
Tbit(ps) = 1000 / BitRate(Gbps)
5) Allowable broadening
Tallow = Tbit × Margin%
6) Design checks
Utilization% = ΔT / Tallow × 100
Max bit rate ≈ 1000 × MarginFraction / ΔT
Max length ≈ Tallow / (|D(λ)| × Δλeff)
Chromatic dispersion is pulse spreading caused by different wavelengths traveling at slightly different speeds. It reduces timing margin and can increase bit errors over long or high-speed optical spans.
The coefficient changes with wavelength. Dispersion slope lets the calculator shift the reference coefficient to the actual operating wavelength, producing a more realistic estimate than a fixed coefficient alone.
A wider optical spectrum experiences more delay spread across the fiber. Narrow-linewidth transmitters usually reduce chromatic dispersion impact, especially on longer spans and higher bit rates.
Chirp is extra spectral broadening produced by modulation behavior in some transmitters. Adding it to source linewidth gives a more complete effective spectrum for dispersion calculations.
Many designers reserve only a fraction of the bit period for chromatic dispersion. Smaller percentages are stricter and safer, while larger percentages accept tighter link timing margins.
No. This tool is excellent for planning, screening, and engineering estimates. Final deployment decisions should also consider attenuation, nonlinear effects, receiver sensitivity, and vendor transceiver limits.
A negative remaining allowance means predicted broadening already exceeds the design budget. That usually points to too much distance, too much spectral width, or a bit rate that is too high.
You can shorten the span, lower the bit rate, use a narrower-linewidth transmitter, shift the wavelength, or add dispersion compensation depending on system design and equipment options.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.