Microring Extinction Ratio Calculator

Estimate microring extinction quickly using measured transmission powers. Or compute from loss and coupling parameters. Check resonance contrast and validate your photonic design today.

Calculator

Choose measured data or a simple all-pass ring model.
Maximum transmitted power near antiresonance.
Minimum transmitted power at resonance dip.
All results are computed using linear power.
0<a<1. Includes propagation and bend loss.
0<r<1. Related to coupling strength of the bus.
Extinction ratio (linear)
—
Power ratio Pmax/Pmin or Tmax/Tmin.
Extinction ratio (dB)
—
10·log10(ER). Easy to compare devices.
Good practice
Use consistent units and positive powers.
Lower Pmin usually means higher contrast.

Formula used

This calculator supports two equivalent definitions of microring extinction ratio.

1) From measured powers

ER = Pmax / Pmin

ER(dB) = 10 · log10(ER)

2) From all-pass ring parameters

Let a be round-trip amplitude transmission and r be self-coupling amplitude.

Tmin = ((a − r)2) / (1 − a r)2

Tmax = ((a + r)2) / (1 + a r)2

ER = Tmax / Tmin

How to use this calculator

  1. Choose a method: measured powers or ring parameters.
  2. Enter the required values using consistent units.
  3. Click Calculate to show results above the form.
  4. Use CSV or PDF buttons to export the computed values.
  5. For ring method, compare a and r to infer coupling regime.

Example data table

Case Pmax (mW) Pmin (mW) ER (linear) ER (dB)
A 1.20 0.03 40.0000 16.0206
B 0.85 0.05 17.0000 12.3045
C 2.00 0.20 10.0000 10.0000

These examples assume linear power in mW.

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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.