Patent ID: 8428470
Filing Date: 2013-04-23
Classification: B82Y,G02F,H01S,H04B,H04J

Abstract:
1. A waveform shaping apparatus comprising: each of a first optical amplifier and a second optical amplifier that is provided with a substrate having layers of quantum dots and that amplifies a plurality of signal beams respectively having a wavelengths corresponding to sizes of the quantum dots and being multiplexed to be wavelength-division multiplexed signal beam; a first applied voltage adjusting unit that adjusts a level of forward bias applied to the first optical amplifier for suppressing noise of the signal by saturating an amplification factor upon determining that noise of the signal exceeds a threshold, the determining being based on obtained information about signal quality; an amplification saturating unit that saturates the amplification factor for each of the signal beams in the wavelength-division multiplexed signal beam going through the first optical amplifier by adjusting power of the signal beams in the wavelength-division multiplexed signal beam to be equal to or greater than predetermined values respectively corresponding to the wavelengths, by applying a positive voltage to the first optical amplifier; a second applied voltage adjusting unit that adjusts a level of reverse bias applied to the second optical amplifier for suppressing noise of the signal by saturating an absorption factor upon determining that noise of the signal exceeds the threshold, the determining being based on obtained information about signal quality; and an absorption saturating unit that saturates the absorption factor for each of the signal beams in the wavelength-division multiplexed signal beam going through the second optical amplifier by adjusting power of the signal beams in the wavelength-division multiplexed signal beam to be under predetermined values respectively corresponding to the wavelengths, by applying a negative voltage to the second optical amplifier.