Photonic CDMA by coherent matched filtering using time-addressed coding in optical ladder networks

We investigate a photonic CDMA system based on coherent matched filtering in ladder networks, employing both time-spreading and selective interference to discriminate wanted from unwanted signals. A theory is presented for time-resolved pulses which takes account of arbitrary source coherence. We examine the key issues of optical source requirement's and phase and polarization control of en/decoder networks. And demonstrate key concepts experimentally. The crosstalk-limited signal-to-noise ratio is shown to be much higher than previous, purely incoherent systems. CDMA systems using coherent matched filtering therefore offer renewed promise for practical high capacity, multigigabit/s, multiuser networks.<
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