This study proposes a spectral polarization coding scheme for the implementation of complementary bipolar optical correlation in a noncoherent optical code-division multiple-access network. The coder-decoders0 are implemented over differential photodetectors based on fiber Bragg gratings and polarization beamsplitters. Traditionally, complementary unipolar spectral amplitude coding (SAC) schemes are used to transmit the specific codeword on data bit 1 and its complementary codeword on data bit 0. In the proposed scheme, the spectral amplitude is incorporated with polarization coding as the specific signature address code. A Walsh-Hadamard code is employed as the signature address to allocate to each specified wavelength to an individual vertical or horizontal state of polarization. The results indicate that multiple-access interference can theoretically be eliminated by correlation subtraction at the differential photodetectors. Neglecting the effects of shot noise and thermal noise, and considering only phase-induced intensity noise with a degree-of-polarization setting of P=0 for the ideal case, the bit error rate (BER) versus the number of simultaneous active users is improved by 43% in the proposed scheme over the complementary unipolar SAC scheme for a 10-9 error probability. Setting P=1 for the worst case, the BER performance of the proposed scheme matches that of the complementary unipolar SAC scheme.
All Science Journal Classification (ASJC) codes
- Atomic and Molecular Physics, and Optics