Absorption saturation nonlinearity in InGaAs/InP p-i-N photodiodes

摘要

Photodiode nonlinearities can degrade the performance of analog optical links and signal processing systems. The reported work to understand and reduce these nonlinearities has focused primarily on the nonlinearity due to electric field screening induced by the photogenerated carriers. This screening decreases the carrier drift velocity, reducing the photodiode bandwidth. Recently, there has been interest in using picosecond optical pulses to sample analog electrical signals in photonic analog-to-digital converters (ADCs). The high carrier densities generated by these short pulses during photodetection can cause absorption saturation ("leaching) which reduces the photodiode's responsivity. In this paper, we present measurements and simulations of this absorption saturation nonlinearity. We also report the development of large area InGaAs/InP p-i-n photodiodes with thick absorbing layers that greatly improve the linearity of an optically sampled ADC.