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We have demonstrated an optical preamplifier with a record sensitivity of -38.8 dBm (102 photons/bit) at 10Gbit/s. When employed in a practical link the sensitivity is only slightly degraded to -37.6dBm (135 photons/bit) by input coupling losses and feedback due to Rayleigh backscattering.
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Laming et al. (1992) studied this question.
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