| 摘要 |
A secure optical communication system and method are disclosed. Short optical pulses are first modulated with data, then dispersed in time so that they spread out over multiple bit periods, then the desired code is applied to the dispersed pulses. The encoding may include frequency shifts or phase shifts or other. The dispersed optical symbols overlap in time so an applied code chip thus acts on multiple symbols simultaneously. There are generally multiple code chips per dispersed symbol. The coding device does not need to be synchronized to the data rate. Multiple wavelength division multiplexed channels may be encoded simultaneously. The signal propagates to a decoder that is synchronized with encoder to apply a complementary code thereby canceling out the effect of the encoder. The encoder and decoder can be realized by varying the wavelength of an optical pump to a parametric amplifier, allowing for a wide-band frequency shift.
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