Optical Detector QE & Responsivity Calculator Formula
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This optical detector calculator allows you to determine the quantum efficiency and responsivity of photodetectors based on input parameters such as wavelength, incident power and photocurrent.
Optical Detector Quantum Efficiency & Responsivity
The quantum efficiency (QE) of an optical detector is the ratio of the number of charge carriers generated to the number of incident photons. It is given by the formula QE = R _ (h _ c) / q * λ
Where:
- R = Responsivity (A/W)
- h = Planck’s constant (6.626 x 10^-34 J·s)
- c = Speed of light (3 x 10^8 m/s)
- q = Elementary charge (1.602 x 10^-19 C)
- λ = Wavelength of incident light (m)

The responsivity (R) of an optical detector is the ratio of the output current to the incident optical power, given by the formula R = I / P Where:
- I = Photocurrent (A)
- P = Incident optical power (W)
Optical Detector Calculator
Optical Detector (e.g. PIN Photodiode) Calculation Example:
- Inputs : Wavelength (λ) = 850 nm, Incident Power (P) = 10 uW, Photocurrent (I) = 5 uA
- Outputs : Responsivity (R) = 0.5 A/W, Quantum Efficiency (QE) = 0.73 i.e. 73%
Conclusion
These calculations are essential for designing and optimizing optical communication systems and photodetector applications. As mentioned, the quantum efficiency indicates how effectively the photodetector converts incident photons into electrical current, while responsivity measures the output current per unit of incident optical power. Higher quantum efficiency means higher responsivity and hence better receiver sensitivity and performance.
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