Hybrid WDM and Optical Spectral Amplitude Coding with Array Waveguide Gratings over Fiber-to-the-Home Network

The hybrid wavelength-division multiplexing and optical code-division multiple-access scheme for EPON (called WDM/OCDMA-EPON) is presented over fiber-to-the-home (FTTH) network. In this study, each ONU (optical network unit) group is assigned the maximal-length sequence (M-sequence) code which is popularly used for spectral amplitude coding in OCDMA network. Hence, the proposed scheme is suitable for various distances between ONU and OLT (optical line terminal). By employing the inherent cyclic and free spectral range (FSR) periodic properties of arrayedwaveguide grating (AWG) router, the AWG coder/decoder (codec) is shared by various ONUs group and then the number of AWGs is significantly decreased. Moreover, the variable degree of polarization (DOP) is investigated to evaluate the influence of the ratio of signal to phase-noise (SNRPIIN). The system performance in terms of simultaneous active ONUs is improved approximating 20% compared to the average DOP of 0.5 when we set up a depolarizer in front of balanced photo-detector.