Incoherent Hybrid Spectral Amplitude and Polarization Coding Implemented over Differential Photo-Detectors

Y.-T. Chang and J.-F. Huang (Taiwan)


Spectral polarization coding (SPC), Spectral amplitude coding (SAC), Fiber Bragg grating (FBG), Optical code division multiple-access (OCDMA), Multiple-access interference (MAI), Phase-induced intensity noise (PIIN).


This study proposes a spectral amplitude/polarization coding (SAC/SPC) scheme for the implementation of bipolar optical correlation in a non-coherent optical code division multiple-access (OCDMA) network. The present coder/decoders (codecs) are implemented over differential photo-detectors based on hybrid fiber Bragg gratings (FBGs) and polarization beam splitters (PBSs). In the proposed scheme, the Walsh-Hadamard code is employed as a signature address to allocate each specified wavelength an individual SOP (i.e. a vertical or horizontal state). Hence, the previous complementary unipolar SAC scheme, which transmitted the specific codeword on data bit one and its complementary codeword on data bit zero, is incorporated with polarization coding (i.e., called hybrid SAC/SPC) as the specific signature address code and is therefore suitable for bipolar spectral systems. The evaluation results indicate that, theoretically, multiple access interference (MAI) can be completely eliminated. Moreover, when only the phase induced intensity noise (PIIN) is considered, and the error probability is given as 10-9 , the correlation between the bit error rate (BER) and the number of simultaneous active users is improved by 43% relative to the conventional complementary unipolar SAC scheme under setting the degree of polarization to P=0 for ideal case.

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