Quasi-analog operation for low photon flux detection with SiPM’s standard and fast outputs

In this paper, we characterize the quasi-analog detection performance of silicon photomultiplier (SiPM) photodetector for optical wireless communications (OWC) at low photon flux signal intensity. In addition to analyzing the specificities of conventional anode-cathode standard output, it also highlights the unique capacitively coupled fast output feature of the off-the-shelf SiPM devices introduced by SensL, now ON Semiconductor (onsemi). Furthermore, the potential advantages of fast output are analyzed, and first propose the combined output model of standard and fast outputs. This combined output can be used to suppress ambient noise utilizing the bipolar characteristics of the fast output amplitude, e.g., the amplitude of the fast output can be up to ±30 mV under a useful signal light intensity of 94.1 nW, which can suppress the ambient noise amplitude of 30 mV and effectively improves signal-to-noise ratio. In addition, an approximate linear quantitative relationship between the standard output voltage amplitude and the SiPM chip received incident optical power was obtained, e.g., at different intensities of dark current and ambient current (1 nA and 2 nA), standard output voltage amplitudes of 90 mV and 50 mV correspond to optical powers of 50.5 nW and 21.3 nW or 34.7 nW and 5.7 nW. Finally, the potential performance of the proposed combined output schemes is confirmed by experimental and the measured Q-factor of the eye diagrams was optimised from 13.03 to 15.08. The proposed onsemi SiPM combined output schemes of standard and fast outputs can be selected to detection analog low-light link.