Random-Fiber Laser Threshold

Compare distributed random-fiber gain with supplied round-trip logarithmic loss.

Description

A distributed gain budget compares gain times fiber length with a supplied logarithmic loss.

A distributed gain budget compares gain times fiber length with a supplied logarithmic loss. Exponentiating yields the round-trip power factor under this convention.^[1]

Compare distributed random-fiber gain with supplied round-trip logarithmic loss.

When to use Random-Fiber Laser Threshold

Use this tool to compare distributed random-fiber gain with supplied round-trip logarithmic loss.

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 Random-Fiber Laser Threshold 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 distributedGainPerMeter, fiberLengthMeters, roundTripLogLoss using the field table and calculation rules, then run the tool.
Read netLogGain, roundTripPowerFactor, aboveThreshold. 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
distributedGainPerMeter	Distributed gain coefficient (1/m)	number	Required
fiberLengthMeters	Fiber length (m)	number; minimum: 0	Required
roundTripLogLoss	Round-trip logarithmic loss	number; minimum: 0	Required

Enter finite signed gain, nonnegative length/loss. Return net log gain, factor and inclusive net≥0 threshold flag.

netLogGain=gainPerMeter×length−logLoss; factor=exp(netLogGain)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
netLogGain	Net logarithmic gain	number
roundTripPowerFactor	Round-trip power factor	number; minimum: 0
aboveThreshold	Above threshold	boolean

json

{
  "input": {
    "distributedGainPerMeter": 0.2,
    "fiberLengthMeters": 10,
    "roundTripLogLoss": 1.5
  },
  "output": {
    "netLogGain": 0.5,
    "roundTripPowerFactor": 1.6487212707001282,
    "aboveThreshold": true
  }
}

Limitations and assumptions

No random-feedback model, spectral gain or factor-of-two path adjustment is added; inputs must use the intended round-trip convention.

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. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Rare-Gas Pump Threshold: Compare absorbed pump power with a supplied rare-gas laser threshold. For a complementary task, use SCOWA Amplifier Output: Estimate SCOWA output from small-signal gain and a supplied saturation ceiling.

References

Random-Fiber Laser Threshold — tool.io

Similar or alternative tools

Rare-Gas Pump Threshold
Compare absorbed pump power with a supplied rare-gas laser threshold.
SCOWA Amplifier Output
Estimate SCOWA output from small-signal gain and a supplied saturation ceiling.