Fabry-Pérot Linewidth
Calculate Fabry–Pérot free spectral range and linewidth from cavity length, index, and finesse.
Description
Fabry–Pérot free spectral range follows linear-cavity round-trip time.
Fabry–Pérot free spectral range follows linear-cavity round-trip time. Finesse divides that spacing to give a linewidth estimate.1
Calculate Fabry–Pérot free spectral range and linewidth from cavity length, index, and finesse.
When to use Fabry-Pérot Linewidth
Use this tool to calculate Fabry–Pérot free spectral range and linewidth from cavity length, index, and finesse.
Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
How to use Fabry-Pérot Linewidth and understand its results
- Prepare the optical measurements, geometry, fitted coefficients or caller-selected thresholds requested. Confirm wavelength, radius/diameter, pulse-width, angle and unit conventions before running the calculation.
- Enter cavityLengthMeters, refractiveIndex, finesse using the field table and calculation rules, then run the tool.
- Read freeSpectralRangeHertz, linewidthHertz. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| cavityLengthMeters | Cavity length (m) | number; minimum: 0 | Required |
| refractiveIndex | Cavity refractive index | number; minimum: 0 | Required |
| finesse | Finesse | number; minimum: 0 | Required |
Enter positive length, refractive index and finesse. Return both frequencies in Hz using c=299792458 m/s.
FSR=c/(2nL); linewidth=FSR/finesse Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| freeSpectralRangeHertz | Free spectral range (Hz) | number; minimum: 0 |
| linewidthHertz | Resonance linewidth (Hz) | number; minimum: 0 |
{
"input": {
"cavityLengthMeters": 0.1,
"refractiveIndex": 1,
"finesse": 100
},
"output": {
"freeSpectralRangeHertz": 1498962290,
"linewidthHertz": 14989622.9
}
}Limitations and assumptions
No mirror reflectivity, loss, dispersion or line-shape fit is performed.
Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Longitudinal Mode Count: Calculate cavity free spectral range and longitudinal modes within a gain bandwidth. For a complementary task, use Microdisk Q Threshold: Derive microdisk loaded Q and threshold material gain, then compare available gain.
References
-
Fabry-Pérot Linewidth — tool.io
Similar or alternative tools
- Longitudinal Mode Count
Calculate cavity free spectral range and longitudinal modes within a gain bandwidth.
- Microdisk Q Threshold
Derive microdisk loaded Q and threshold material gain, then compare available gain.