Confidential enhancement with programmable spectral phase coding over fiber-to-the-home access network

A new programmable AWG-Based spectral phase coding OCDMA scheme with changing phase state mechanism is configured over a fiber-to-the-home (FTTH) network. In order to improve BER and confidentiality of conventional spectral phase coding (SPC) OCDMA scheme, the proposed scheme employ complementary SPC code with Hadamard code as signature address codeword and exploit changing codeword mechanism. By performing optical beat detection mechanism, the set of inputs (i.e., each with a phase 0 or π) would correspond to an idealized unmodulated mode-locked laser signal with one mode per phase-encoding bin, conventional SPC is still vulnerable by such eavesdropping. To further overcome conventional SPC for confidential weakness, the proposed programming complementary SPC scheme is configured to protect against even eavesdropper using either simple photo-detector or optical beat detector to detect ONU codeword. In such case, the proposed scheme achieve confidentiality because that eavesdroppers is lacked the changing codeword mechanism based on the initial phase state and shift step T_s knowledge. Compared to conventional SPC OCDMA scheme, the proposed scheme not only achieves better BER as well as confidentiality under eavesdropper attacking by using optical beat detector.