Efficient Low-Dark-Count Detector for Photon Counting

Voxtel has demonstrated efficient high-speed photon counting with thresholded linear-mode avalanche photodiode (APD) receivers using multi-gain-stage InGaAs/InAIAs APDs. In contrast to Geiger APDs, thresholded photon-counting linear APD receivers are thought not to suffer afterpulsing, and can support maximum count rates (MCR) up to 2 or 3 orders of magnitude faster than Geiger APDs. However, the early embodiments of this new photon-counting receiver have a much higher dark count rate (DCR) than InGaAs Geiger-mode APDs. In the Phase II project, Voxtel proposes to reduce the dark count contributions from both the APD and the transimpedance amplifier by developing a new embodiment of the multi-stage APD in the Phase II program that substitutes InP for InAIAs in the multiplier, and simultaneously by fundamentally improving the amplification using a new, ultra-low-noise capacitive-feedback transimpedance amplifier (CTIA).