Detection Characteristics Error Performance analysis of High-speed Optical PPM Communication Systems with an SNSPD

In this paper, we investigate high-speed optical wireless communication systems that use pulse-position-modulation (PPM) and superconducting nanowire single-photon detectors (SNSPDs). We focus on scenarios where the dead time of the SNSPD is longer than a PPM symbol time. To estimate the photon detection probability for each PPM time slot, we utilize Markov chain analysis. Our findings show that the photon detection probability increases with the index of PPM time slot, meaning that the PPM time slot at the end of the symbol has a higher photon detection probability than that at the beginning of a PPM symbol. Using this probability, we derive closed-form expressions for the symbol error rate and channel coding rate of laser PPM systems. We validate our theoretical analysis with Monte-Carlo simulation results. Additionally, we show that optimizing the code rate of channel coding is possible by taking into account the order of PPM and the optical power received at the receiver.