Improving performance of photodetectors using nano photonic structures

Abstract

  Silicon Photomultipliers (SiPMs) are widely used in many kinds of application, such as high-energy physics experiments, light detection and raging, flow cytometry thanks to its excellent photon counting characterization. SiPM contains single-photon avalanche diode (SPAD) arrays. The gap of each SPAD placed trench areas for shielding cross-talk. However, trench areas are known to be an area of low-photo sensitive as well as crosstalk suppression. Therefore, imping photons penetrate into the trench area of the SPAD negatively affects the photon detection efficiency (PDE) and timing performance of the SiPM. Here, we proposed the focused incident photons onto the photo sensitive area of the SPAD using metalens for improving the PDE and timing performance of the SiPMs. We successfully fabricated metalens array corresponding to its SPAD array’s size. After evaluating the focusing characterization of the metalens, we obtained the full width at half maximum (FWHM) of the focusing spot was ~ 1 μm. In addition, we experimentally demonstrated the effectiveness of using metalens for evaluating the PDE and timing performance of the SiPM. The improvement ratio of the PDE and time resolutions were 9.9%, 5.7%, respectively. This study shows the potential for using metalenses for versatile applications of SiPMs.