Monolithic integration metalens in the entire matrix of the silicon photomultipliers for improving the performance of the silicon photomultipliers

Abstract

Silicon photomultiplier (SiPMs) is a photon counting device that consists of single photon avalanche diodes (SPADs) arrays being operated at a Geiger mode and has been widely used in many kinds of application including high-energy physics, confocal laser scanning microscopy (CSLM), flow cytometry, and light detection and ranging (LiDAR) instead of photomultiplier tube (PMT). Trench structures basically places at the boarder of every SPAD to guard optical and electrical crosstalk. However, illuminating photons to the trench region restricted the performance of SiPM such as photon detection efficiency (PDE) and timing performance because it does not absorb photon sufficiently. Our previous work demonstrated that guiding incident photons into the photo sensitive area of SPADs using metalens array resulted in improvement of the performance of the SiPM. However, performance is expected to fluctuate due to misalignment caused by slight vibration because metalens and SiPMs are separated configuration. Guaranteeing a good alignment between the metalens and SiPM has been necessary for practical applications. Here, we demonstrate the completely monolithic integration of a metalens with its corresponding SPAD to provide stable PDE improvement while maintaining the compact and flatness of the optical device. Furthermore, we investigated the crosstalk and dark-current comparing with a reference SiPM without the metalens for investigating the negative effect of integrating metalens with the SiPM. From the results of sophisticated investigation, we show the more practical approach toward the improving overall performance of the SiPM not only the PDE and timing performance but also crosstalk and dark current. Finally, we will show our next perspective and progress towards near infrared application.