Calculator Inputs
Use practical detector values. Large screens show three columns. Smaller screens show two or one column automatically.
Plotly Graph
The graph shows RMS current components in nanoamps. It switches to example mode before calculation.
Example Data Table
| Scenario | Power (mW) | Wavelength (nm) | Bandwidth (MHz) | η | F | S | Q Parameter | Noise (dB) | Total RMS (nA) | State |
|---|---|---|---|---|---|---|---|---|---|---|
| Balanced reference detector | 0.80 | 1,064.00 | 5.00 | 0.90 | 1.00 | 1.00 | 1.822845 | 2.6075 | 42.4799 | Above shot-noise limit |
| Cooled low-dark photodiode | 1.20 | 1,310.00 | 10.00 | 0.88 | 1.00 | 0.85 | 1.385484 | 1.4160 | 70.3810 | Above shot-noise limit |
| Avalanche receiver path | 0.50 | 850.00 | 20.00 | 0.76 | 2.40 | 1.00 | 6.369411 | 8.0410 | 103.1224 | Above shot-noise limit |
Formula Used
This calculator models detector noise against the shot-noise reference. The reported quantum noise parameter is a normalized variance ratio.
A value near 1 indicates shot-noise-limited behavior. Values above 1 show excess noise. Values below 1 suggest sub-shot-noise operation when squeezing dominates.
How to Use This Calculator
- Enter optical power in milliwatts.
- Provide the detector wavelength in nanometers.
- Set your measurement bandwidth in megahertz.
- Enter quantum efficiency as a decimal from 0 to 1.
- Add dark current, temperature, and load resistance values.
- Use excess noise factor above 1 for avalanche behavior.
- Use squeezing factor below 1 for reduced quantum variance.
- Press the calculate button to view results above the form.
- Review the graph, table values, and detector classification.
- Download the result set as CSV or PDF.
Frequently Asked Questions
1. What does the quantum noise parameter represent?
It compares total measured variance with the shot-noise reference. A value of 1 means ideal shot-noise-limited behavior. Larger values show extra noise sources.
2. What does a value below 1 mean?
A result below 1 indicates sub-shot-noise performance. This usually appears when squeezed states reduce optical variance more than other noises add back.
3. Why is wavelength included?
Wavelength changes photon energy and detector responsivity. Those terms directly affect photon rate, photocurrent, and the reference shot-noise level.
4. Why does bandwidth increase noise?
Shot, dark, and thermal noise all grow with measurement bandwidth. Wider bandwidth captures more fluctuations, so RMS noise becomes larger.
5. When should I change the excess noise factor?
Increase this factor for devices with multiplication noise, such as avalanche photodiodes. Leave it at 1 for simple photodiodes without excess gain noise.
6. What is the squeezing variance factor?
It scales the optical shot variance. Use 1 for ordinary coherent light. Use values below 1 when squeezed light reduces quantum fluctuations.
7. Can this page replace a full detector simulator?
No. It is a fast engineering estimator. It ignores frequency-dependent electronics, saturation, impedance mismatches, and many device-specific nonlinear effects.
8. Which units should I enter?
Enter power in mW, wavelength in nm, bandwidth in MHz, dark current in nA, temperature in K, and resistance in ohms.