RESUMO
In this paper, the mathematical description of the temporal self-imaging effect is studied, focusing on the situation in which the train of pulses to be dispersed has been previously periodically modulated in phase and amplitude. It is demonstrated that, for each input pulse and for some specific values of the chromatic dispersion, a subtrain of optical pulses is generated whose envelope is determined by the Discrete Fourier Transform of the modulating coefficients. The mathematical results are confirmed by simulations of various examples and some limits on the realization of the theory are commented.
RESUMO
A coding/decoding setup for a spectral phase encoding optical code-division multiple access (SPE-OCDMA) system has been developed. The proposal is based on the temporal self-imaging effect and the use of an easily tunable electro-optic phase modulator to achieve line-by-line coding of the transmitted signal, thus assuring compatibility with WDM techniques. Modulation of the code is performed at the same rate as the data, avoiding the use of high-bandwidth electro-optic modulators. As proof of concept of the technique, experimental results are presented for a back-to-back coder/decoder setup transmitting a 10 GHz unmodulated optical pulse train within an 80 GHz optical window and using 8-chip Hadamard codes.