Calculated Results
Results appear here after submission and stay above the form.
| Derived Quantity | Value |
|---|
Engineering Input Panel
Use the grid below. Large screens show three columns, smaller screens show two, and mobile shows one.
Plotly Graph
The plot compares total phase and wrapped phase across the selected sweep variable.
Example Data Table
| Scenario | λ (nm) | L (mm) | n₀ | nref | ΔT (°C) | dn/dT | α | Extra Path (µm) | OPD (µm) | Wrapped Phase (°) |
|---|---|---|---|---|---|---|---|---|---|---|
| Fiber arm mismatch | 1550 | 10 | 1.4682 | 1.4670 | 12 | 1.1e-5 | 5.5e-7 | 0.20 | 13.5201 | 260.1495 |
| Thin-film branch | 850 | 2 | 2.1800 | 2.1750 | 5 | 3.0e-5 | 2.0e-6 | -0.05 | 10.2501 | 21.2201 |
| Sensor cavity | 633 | 1.5 | 1.5200 | 1.5000 | 0 | 0 | 0 | 0 | 30.0000 | 141.6114 |
Formula Used
1) Temperature-adjusted effective index
n(T) = n₀ + (dn/dT) × ΔT
2) Temperature-adjusted physical length
L(T) = L₀ × [1 + α × ΔT]
3) Optical path difference
OPD = [n(T) - nref] × L(T) + ΔLextra
4) Optical phase shift
φ = (2π / λ₀) × OPD
5) Wrapped phase and cycles
Wrapped Phase = φ mod 2π
Cycles = OPD / λ₀
This structure works well for interferometers, fiber imbalance checks, thin-film optical branches, waveguide modulators, and thermal phase tuning studies.
How to Use This Calculator
- Enter the source vacuum wavelength and choose its unit.
- Enter the physical propagation length and its unit.
- Provide the base effective index and the reference index.
- Add temperature change, thermo-optic coefficient, and thermal expansion if relevant.
- Enter any extra path difference caused by geometry, biasing, or packaging.
- Select the graph sweep variable and optionally set custom graph limits.
- Press the calculate button to show results below the header and above the form.
- Review total phase, wrapped phase, cycles, OPD, and download CSV or PDF reports.
FAQs
What does this calculator measure?
It computes optical phase shift from wavelength, effective index, reference index, physical length, thermal effects, and any extra optical path difference.
When should I use a reference index?
Use a reference index when comparing one optical arm against another, such as interferometers, directional couplers, Mach-Zehnder modulators, and sensing branches.
Why does wrapped phase differ from total phase?
Total phase keeps accumulating with path difference. Wrapped phase folds that result into one 0° to 360° cycle, which is easier for interference interpretation.
What wavelength should I enter?
Enter the vacuum wavelength of the source. The calculator internally combines that with effective refractive index to obtain phase accumulation in the device.
How is temperature included?
Temperature changes the effective index through dn/dT and changes the physical length through the linear expansion coefficient. Both effects alter optical path difference.
Can this help with fiber and waveguide design?
Yes. It is useful for fiber delay lines, waveguide modulators, thin-film stacks, interferometric sensors, and any system where phase matching matters.
What if my result is very large?
Large phase values are normal for long paths or strong index differences. Wrapped phase is usually the practical value for fringe or modulation interpretation.
What does the graph show?
The graph sweeps length, wavelength, or temperature and plots both total phase and wrapped phase so sensitivity and tuning ranges are easy to inspect.