Photodetector Nonlinearities Due to Voltage-Dependent Responsivity

A newly quantified photodiode nonlinearity is derived from a previously known bias voltage-dependent responsivity. For an InGaAs p-i-n photodiode, measured harmonic distortion is shown to be dominated by this derived nonlinearity mechanism. It is also shown that electron ionization in the depletion region of the photodiode is the source of the voltage-dependent responsivity.