Improved phase noise performance using orthogonal ternary codes over spectral polarization and amplitude coding networks

Jen-Fa Huang Yao-Tang Chang National Cheng Kung University Advanced Optoelectronic Technology Center Department of Electrical Engineering Institute of Computers and Communications Tainan, Taiwan E-mail: [email protected] Abstract. This study proposes an improved hybrid scheme of spectral polarization coding SPC and spectral amplitude coding SAC based on a specified orthogonal ternary sequence. In a previous SPC scheme, the entire wavelength was assigned either a vertical or a horizontal state of polarization. However, this study assigns positive, negative, or null chip values to individual wavelengths to create an orthogonal ternary sequence based on the bipolar Walsh-Hadamard matrix. This approach reduces the number of wavelength collisions at the photodetector and hence reduces the phase-induced intensity noise PIIN . Neglecting the effects of shot noise and thermal noise, we consider only PIIN with a degree of polarization P=0. The proposed scheme improves the bit error rate by 40% and 100% over SPC and complementary unipolar SAC schemes. The number of simultaneous active users supported by the hybrid scheme for the worst case P=1 is improved by 41.3% over the complementary unipolar SAC coding scheme for the ideal case P=0 . © 2007 Society of Photo-Optical Instrumentation Engineers. DOI: 10.1117/1.2432883