Photons in Focus

In this project, Photons in Focus, researchers from The Hague University of Applied Sciences will work together with the company Photosynthetic to fabricate high-quality microlenses that will optimally focus light onto microscopic light detectors. Specifically, the microlenses will be designed to focus light onto superconducting nanowire single-photon detectors (SNSPDs) from the company Single Quantum. SNSPDs are cryogenic single-photon detectors with photon detection efficiencies up to 99% and timing resolutions down to 15 picosecond. Recently, Single Quantum has been developing arrays of SNSPDs for free-space biomedical imaging and deep space communications. The photon detection efficiency of these arrays is suboptimal, because 15-20% of the light falls onto nonsensitive areas. In Photons in Focus, fabrication of two types of microstructures will be explored for optimally focusing light onto these SNSPDs and improving the photon detection efficiency. First, 3-dimensional microlenses will be created at Photosynthetic using their method of dual-wavelength volumetric microlithography. Second, phase-reversal Fresnel zone plates will be fabricated using standard 2-dimensional photolithography at The Hague University of Applied Sciences. Both types of microstructures will be tested for their focusing properties and potential optical losses, and their ability to enhance to photon detection efficiency of SNSPDs in cryogenic conditions.