PPM demodulation: On approaching fundamental limits of optical communications

TL;DR

This paper introduces a novel optical receiver for M-ary pulse-position modulation that surpasses existing methods in error performance and approaches quantum limits by integrating photodetection, phase control, and parametric amplification.

Contribution

It proposes a structured receiver design that achieves lower error rates and approaches fundamental quantum limits in optical PPM demodulation.

Findings

The proposed receiver outperforms all known demodulation schemes in error probability.

It approaches the quantum limit of optical communication performance.

The framework defines ultimate spectral and photon efficiency tradeoffs.

Abstract

We consider the problem of demodulating M-ary optical PPM (pulse-position modulation) waveforms, and propose a structured receiver whose mean probability of symbol error is smaller than all known receivers, and approaches the quantum limit. The receiver uses photodetection coupled with optimized phase-coherent optical feedback control and a phase-sensitive parametric amplifier. We present a general framework of optical receivers known as the conditional pulse nulling receiver, and present new results on ultimate limits and achievable regions of spectral versus photon efficiency tradeoffs for the single-spatial-mode pure-loss optical communication channel.