Cavity Ring-Down Reflectivity
Extract effective round-trip reflectivity and loss from cavity ring-down time.
Description
Cavity ring-down describes exponential decay of stored optical power.
Cavity ring-down describes exponential decay of stored optical power. The measured lifetime estimates effective loss for an entire round trip, rather than a single mirror.1
Extract effective round-trip reflectivity and loss from cavity ring-down time.
When to use Cavity Ring-Down Reflectivity
Use this tool to extract effective round-trip reflectivity and loss from cavity ring-down time.
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 Cavity Ring-Down Reflectivity 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 roundTripLengthMeters, ringDownTimeSeconds using the field table and calculation rules, then run the tool.
- Read effectiveRoundTripReflectivity, roundTripLossPpm. 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 |
|---|---|---|---|
| roundTripLengthMeters | Cavity round-trip length (m) | number; minimum: 0 | Required |
| ringDownTimeSeconds | Intensity ring-down time (s) | number; minimum: 0 | Required |
Enter positive round-trip length in meters and decay time in seconds. Use c=299792458 m/s and return effective reflectivity and loss ppm.
R=exp(−roundTripLength/(c lifetime)); lossPpm=1e6(1−R) Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| effectiveRoundTripReflectivity | Effective round-trip reflectivity | number; minimum: 0; maximum: 1 |
| roundTripLossPpm | Round-trip loss (ppm) | number; minimum: 0 |
{
"input": {
"roundTripLengthMeters": 0.2,
"ringDownTimeSeconds": 0.000001
},
"output": {
"effectiveRoundTripReflectivity": 0.9993330942901378,
"roundTripLossPpm": 666.9057098621645
}
}Limitations and assumptions
No decay fit, medium-index correction or separation of mirror, absorption and scattering losses 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 Cavity Path Enhancement: Calculate geometric cavity path enhancement from effective reflectivity. For a complementary task, use Cavity Polarimetry Sensitivity: Estimate cavity-enhanced polarimetry rotation sensitivity from finesse and detector noise.
References
-
Cavity Ring-Down Reflectivity — tool.io
Similar or alternative tools
- Cavity Path Enhancement
Calculate geometric cavity path enhancement from effective reflectivity.
- Cavity Polarimetry Sensitivity
Estimate cavity-enhanced polarimetry rotation sensitivity from finesse and detector noise.