Arabskyj, L; Dejen, B; Santana, T S; Lucamarini, M; Chunnilall, C; Dolan, P R (2025) Interference effects in commercially-available free-space silicon single-photon avalanche diodes. Applied Physics Letters, 125. 194003

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Abstract

Single-photon avalanche diodes (SPADs) are critical components for performing photon-based quantum measurements, many of which would benefit from a spatially uniform detector response. This is especially true in metrology and applications where the spatial location of incident photons may vary with time. We report on interference effects in commercially-available silicon SPADs that are detrimental to their spatial uniformity. Contrasts as high as 18% have been observed; these effects have the potential to significantly affect applications which utilize coherent light and require constant detection efficiencies. We eliminate the device optical window as a contributing interface, isolating likely causes to anti-reflective coatings, the semiconductor surface, and the SPAD’s internal structure. We also present results where we leverage this sub-optimal behavior by aligning an incident beam with the position of maximum constructive interference, yielding an effective detection efficiency of 51.1(6)% compared to the normal value of 44.3(5)% obtained with the interference suppressed. We anticipate that this work will have a significant impact on the continuing development of these devices, methods for characterizing them, and will be informative for end users.

Item Type:	Article
Subjects:	Optical Radiation and Photonics > Few Photon Science
Divisions:	Quantum Technologies
Identification number/DOI:	10.1063/5.0225337
Last Modified:	07 Mar 2025 14:43
URI:	https://eprintspublications.npl.co.uk/id/eprint/10132