Optical nonreciprocity is required in many optical systems for signal stabilization, laser protection, non-destructive probing. Here, we experimentally demonstrate a nonreciprocal fiber-optic amplifier enabled by encircling-an-exceptional-point emulation and gain-saturation nonlinearity. We realize the proposed system by combining optical attenuators, Erbium-doped fiber amplifiers (EDFA), and 2x2 couplers. We obtain remarkably high nonreciprocal transmission ratio > 20 dB persisting over the entire gain band from 1,530 to 1,560 nm at moderate input power conditions from 0.1 to 1 mW.
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