Semiconductor optical integrated element

A semiconductor optical integrated element having a first end surface and a second end surface opposite to the first end surface, the semiconductor optical integrated element comprising:

• a semiconductor substrate;
• a first optical amplifier which is provided on the semiconductor substrate and has one end contacting with the first end surface, and which amplifies a signal beam inputted from the first end surface, along an optical waveguide;
• a first passive optical waveguide which is provided on the semiconductor substrate and connected to another end of the first optical amplifier, and which guides the amplified signal beam toward a direction different from a direction of the optical waveguide;
• an optical splitter which is provided at the first passive optical waveguide and splits the guided signal beam into a plurality of signal beams;
• a phase modulator which is provided on the semiconductor substrate and connected to each of a plurality of the branched first passive optical waveguides, and which performs phase modulation on the plurality of signal beams along the different direction;
• a second passive optical waveguide which is provided on the semiconductor substrate and has one end connected to the phase modulator, and which guides each phase-modulated signal beam toward the direction of the optical waveguide from the different direction;
• an optical multiplexer which is provided at the second passive optical waveguide and multiplexes the plurality of phase-modulated signal beams into one signal beam;
• and
• a second optical amplifier which is provided on the semiconductor substrate such that one end of the second optical amplifier is connected to another end of the second passive optical waveguide and another end of the second optical amplifier contacts with the first end surface or the second end surface, and which amplifies the signal beam guided by the second passive optical waveguide, along the direction of the optical waveguide, and outputs the amplified signal beam to outside, an optical confinement factor of the second optical amplifier being greater than that of the first optical amplifier, wherein
• an optical waveguide length of the first optical amplifier and an optical waveguide length of the second optical amplifier are equal, and
• a first gain core layer of the first optical amplifier and a second gain core layer of the second optical amplifier are each formed by a multiple quantum well structure, and a total number of well layers in the multiple quantum well structure forming the second gain core layer is larger than a total number of well layers in the multiple quantum well structure forming the first gain core layer.

A semiconductor optical integrated element having a first end surface and a second end surface opposite to the first end surface, the semiconductor optical integrated element comprising:

• a semiconductor substrate;
• a first optical amplifier which is provided on the semiconductor substrate and has one end contacting with the first end surface, and which amplifies a signal beam inputted from the first end surface, along an optical waveguide;
• a first passive optical waveguide which is provided on the semiconductor substrate and connected to another end of the first optical amplifier, and which guides the amplified signal beam toward a direction different from a direction of the optical waveguide;
• an optical splitter which is provided at the first passive optical waveguide and splits the guided signal beam into a plurality of signal beams;
• a phase modulator which is provided on the semiconductor substrate and connected to each of a plurality of the branched first passive optical waveguides, and which performs phase modulation on the plurality of signal beams along the different direction;
• a second passive optical waveguide which is provided on the semiconductor substrate and has one end connected to the phase modulator, and which guides each phase-modulated signal beam toward the direction of the optical waveguide from the different direction;
• an optical multiplexer which is provided at the second passive optical waveguide and multiplexes the plurality of phase-modulated signal beams into one signal beam;
• and
• a second optical amplifier which is provided on the semiconductor substrate such that one end of the second optical amplifier is connected to another end of the second passive optical waveguide and another end of the second optical amplifier contacts with the first end surface or the second end surface, and which amplifies the signal beam guided by the second passive optical waveguide, along the direction of the optical waveguide, and outputs the amplified signal beam to outside, an optical confinement factor of the second optical amplifier being greater than that of the first optical amplifier, wherein
• an optical waveguide length of the second optical amplifier is smaller than an optical waveguide length of the first optical amplifier, and
• a first gain core layer of the first optical amplifier and a second gain core layer of the second optical amplifier are each formed by a multiple quantum well structure, and a total number of well layers in the multiple quantum well structure forming the second gain core layer is larger than a total number of well layers in the multiple quantum well structure forming the first gain core layer.