Microlenses replicated on front-illuminated single-photon avalanche diodes (SPAD) or back-illuminated CMOS image sensor are found to be stable to temperature variations, exposure to humidity, mechanical shocks and vibrations, as well as irradiation by gamma rays (for space applications). They highly improve the effective fill-factor, on front-illuminated SPAD-based image sensors, and the parasitic light sensitivity on a back-illuminated CMOS image sensor. Their broad transmission spectrum from NUV to NIR, combined with the wide geometrical space available to fabricate microlenses on various active substrates (wafer or die down to 2×2 mm2), make them suitable to a wide range of quantum photonics applications.
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