Sensitivity of direct-detection lightwave receivers using optical preamplifiers

A simple technique for analyzing the sensitivity and bit-error-rate (BER) performance of direct-detection lightwave receivers using optical preamplifiers is presented. The analysis provides closed-form expressions for the system performance and includes the impact of phase noise. For a negligible linewidth, the theory predicts an average signal energy of 42.3 photons/bit at a BER of 10/sup -9/. For comparison, a more accurate analysis predicts an average signal energy of 38 photons/bit under the same conditions.<
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