Mathematical proof of errors in Capasso's excess noise factor formula for an n-step staircase multiplier
Abstract
Solid-state devices such as multistep staircase avalanche photodiodes (APDs) are analogues to the photomultiplier tubes and are considered as a cascade-amplifier. The major source of internal noise in these APDs is due to the randomness in their stepwise impact ionization. Recent literature on staircase APDs by research groups such as Campbell and co-workers have reported the theoretical estimates of total excess noise factors using Capasso's excess noise factor formula. This formula is based on Friis' total noise factor formula for cascade networks. This article proves that Capasso's formula for a staircase APD, erroneously considers the power gains in Friis' total noise factor formula as the gains.
Keywords
Cite
@article{arxiv.2506.09649,
title = {Mathematical proof of errors in Capasso's excess noise factor formula for an n-step staircase multiplier},
author = {Ankitha E Bangera},
journal= {arXiv preprint arXiv:2506.09649},
year = {2025}
}
Comments
Recent research articles that have used Capasso's formula have been published in famous research journals, which include 'Nature Photonics (2021)' and 'Optics (2023).' It is important that the research community is aware that Capasso's formula and its equivalent forms are incorrect. This article points out the errors in the formulas (5 pages, No figures, preprint is under submission)