Noise suppression and optical ASE modulation in saturated semiconductor optical amplifiers

We present the modeling and experiment on the noise suppression of high speed modulation signals using a saturated semiconductor optical amplifier (SOA). The noise suppression is enhanced in a high frequency region with increasing the length of a saturated SOA. A novel optical preamplifier using optical modulation of amplified spontaneous emission from a saturated SOA is also presented, exhibiting receiver sensitivity improvements at 10 Gbps. In addition, some results on noise suppression in an optical signal regenerator based on cascaded wavelength converters are discussed.