Optical signal processing method and apparatus

An optical signal processing method, comprising the steps of:

• injecting carriers into a plurality of quantum dots by applying a bias voltage to semiconductor regions of first and second semiconductor optical amplifiers, the plurality of quantum dots for three-dimensionally confining carriers being distributed in each of the semiconductor regions;
• inputting same multiplex signals obtained by time-division multiplexing a plurality of optical pulse signals to both of the first and second semiconductor optical amplifiers and inputting an optical control signal only to the first semiconductor optical amplifier synchronously with a time slot corresponding to one the optical pulse signals constructing the multiplex signal;
• and
• making the multiplex signals output from the first and second semiconductor optical amplifiers interfere with each other to separate one optical signal from the multiplex signal.

An optical signal processing apparatus, comprising:

• first and second semiconductor optical amplifiers each having a semiconductor region, a plurality of quantum dots for three-dimensionally confining carriers being distributed in the semiconductor region;
• a first optical unit for inputting same multiplex signals obtained by time-division multiplexing a plurality of optical pulse signals to both of the first and second semiconductor optical amplifiers;
• a second optical unit for inputting an optical control pulse signal only to the first semiconductor optical amplifier synchronously with a time slot corresponding to one of the optical pulse signals constructing the multiplex signal;
• and
• an interferometer for making multiplex signals output from the first and second semiconductor optical amplifiers interfere with each other to separate one of the optical pulse signals from the multiplex signal.

An optical signal processing apparatus, comprising:

• first and second semiconductor optical amplifiers each having a semiconductor region, a plurality of quantum dots for three-dimensionally confining carriers being distributed in the semiconductor region;
• a first optical unit for inputting an optical pulse signal to the first and second semiconductor optical amplifiers;
• a second optical unit for inputting an optical control pulse signal only to the first semiconductor optical amplifier;
• and
• an interferometer for making optical pulse signals output from the first and second semiconductor optical amplifiers interfere with each other to separate an optical pulse from the optical pulse signals, the optical pulse being synchronous with the optical control pulse signal.

An optical signal processing apparatus comprising:

• an optical absorbing and saturating element for absorbing a component of incident light having an intensity equal to or lower than a threshold value and allowing a component through, having an intensity higher than the threshold value;
• a first optical unit for inputting an optical pulse signal to said optical absorbing and saturating element;
• and
• a semiconductor optical amplifier having a semiconductor region, an optical pulse signal output from said optical absorbing and saturating element is input to said semiconductor optical amplifier, and a plurality of quantum dots for three-dimensionally confining carriers being distributed in the semiconductor region.

An optical signal processing apparatus comprising:

• a plurality of optical absorbing and saturating elements each for absorbing a component of incidence light having an intensity equal to or lower than a threshold value and allowing a component through, having an intensity higher than the threshold value;
• a plurality of semiconductor optical amplifiers each having a semiconductor region, a plurality of quantum dots for three-dimensionally confining carriers being distributed in the semiconductor region;
• and
• optical wave guides for connecting said plurality of optical absorbing and saturating elements and semiconductor optical amplifiers in tandem.