Dynamic Bias APD Receiver Array

Alphacore team will design, develop and demonstrate an innovative avalanche photodiode (APD) focal plane array (FPA) that employs dynamic biasing to increase low-noise gain and detectivity. Alphacore partners are internationally recognized experts - Prof. Joe Campbell (University of Virginia) and consultant Prof. Seth Bank (University of Austin at Texas) - known for pioneering contributions to high-speed, low-noise avalanche photodiodes (APDs) used in optical communication systems. Alphacore’s technique combines the advantages of the two conventional APD operations: Geiger-mode APDs providing single photon sensitivities and linear mode APDs producing a signal proportional to the number of incident photons providing intensity image information. The goal is to dynamically bias the APD such that the charge carriers are speed-controlled and multiply inside of the avalanche region so that their probability of impact ionization as a function of time is maximized. The APD’s gain (and excess noise factor) is manipulated so the signal to noise ratio (at a specific wavelength and bandwidth) can be optimized. This innovation provides a highly sensitive solution for military electro-optical systems operating in low photon flux conditions. Alphacore will design and develop the readout integrated circuit (ROIC) and Prof. Campbell’s team will model, fabricate and characterize the APD samples.