Optical preamplifier using inverted signal ofamplified spontaneous emission in saturatedsemiconductor optical amplifier

A novel optical preamplifier using the optical modulation of amplified spontaneous emission (ASE) in a semiconductor optical amplifier (SOA) is demonstrated. The input signal is converted to the modulation of the ASE due to saturation characteristic in an SOA. The receiver sensitivity was improved by 10 dB at 1 Gbit/s using the proposed preamplifier. The proposed device can not only amplify optical signal but also suppress the intensity noise of the input signal under saturation regime. The intensity noise of 1 Gbit/s spectrum-sliced light was significantly suppressed using the nonlinear characteristic of the preamplifier.