An all-optical bit-error indicating scheme based on self-phase modulation and filtering

In this paper, a novel all-optical bit-error indicating scheme is numerically studied. The bit-error indicating function is achieved by two all-optical processing stages. Firstly, the amplified original bit stream propagates through a high-nonlinear fiber and experiences self-phase modulation which causes intensity-dependent spectrum broadening and split. And then, the bit stream output from the high-nonlinear fiber is filtered by a band-pass filter with the same central wavelength as the original bit stream to generate an error bit indicating signal. The error bit indicating signal, in which only the “Error” bits have the highest peak power, is synchronous with the delayed original bit stream. Therefore, the position of the “Error” bits in the original bit stream can be identified by setting only one judge threshold in the error bit indicating signal. The scheme is demonstrated for an 80 Gb/s bit stream with return-to-zero format by simulation. The results show that the scheme can be used for the all-optical bit-error indicating of the super high bit-rate systems using the return-to-zero format which is favored in the optical time division multiplexing transmission systems.