Implementation and Evaluation of SiPM-Based Photon Counting Receiver for IoT Applications

Silicon photomultipliers (SiPMs) are photon-counting detectors with great potential to improve the sensitivity of optical receivers. Recent studies of SiPMs in communication focus on the speed rather than the power consumption of the receiver. The gain bandwidth product (GBP) of the amplifiers in these post-SiPM readout circuits is significantly higher than the target data rate. Additionally, the SiPM experiments for optical communication are performed using an offline method which uses instruments, including oscilloscopes and personal computers, to process chunks of the transmitted data. In this work, we have developed an embedded real-time field-programmable gate array (FPGA)-based system to evaluate a commercially available 1 mm-sq SiPM. The implemented real-time system achieves data rates from 10 kb/s to 1 Mb/s with a bit error rate (BER) below 1E-3 approaching the Poisson limit. Results showed that reducing either the dark count rate or increasing the data rate leads to lower dark counts per bit time, hence less power penalty to maintain a probability of error (PE) of 1E-3. The numerically simulated results indicated that to maintain the Poisson limit, the minimum GBP of the amplifier in the post-SiPM readout circuit is 120 MHz based on the proposed setup within the tested data rates. This GBP limitation is determined by the noise floor of the read-out circuit. The analysis of the minimum GBP and electrical power consumption of the receiver in photon counting and BER enables the potential future adoption of this receiver technology when high-optical sensitivity is required, such as visible light communications (VLCs) for low-data rate Internet of Things (IoT) applications.