Laser diode, method for manufacturing laser diode and passive optical network system

A manufacturing method of a laser diode comprising:

• providing a semiconductor substrate;
• growing a waveguide layer on the semiconductor substrate, wherein the waveguide layer comprises a quantum well layer that have a plurality of quantum well regions, and the quantum well regions are disposed along a transmission direction of a light wave and respectively have gain peaks of different wavelengths;
• forming a light wave limiting layer on a surface of the waveguide layer;
• wherein the growing the waveguide layer on the semiconductor substrate comprises:
• generating a mask that has a specific pattern on a surface of the semiconductor substrate, wherein the mask has a plurality of mask pattern regions, and each of the mask pattern regions respectively comprises two mask patterns and an intermediate blank region that is located between the two mask patterns;
• and
• performing crystal growth on the semiconductor substrate by using the mask to form the quantum well layer, wherein the plurality of quantum well regions are grown respectively on the intermediate blank regions of the mask pattern regions.

A passive optical network system, comprising:

• an optical line terminal and a plurality of optical network units, wherein the optical line terminal is connected to the optical network units through an optical distribution network;
• and the optical line terminal comprises a plurality of first laser diodes, wherein each of the first laser diode comprises:
• a semiconductor substrate;
• a waveguide layer disposed on the semiconductor substrate, the waveguide layer comprising a quantum well layer;
• a light wave limiting layer disposed on a surface of the waveguide layer, the light wave limiting layer being configured to limit a light wave to be transmitted within the waveguide layer;
• wherein the quantum well layer comprises a plurality of quantum well regions disposed along a transmission direction of the light wave and the quantum well regions respectively have gain peaks of different wavelengths;
• wherein the quantum well layer has a stepped structure, and the quantum well regions have thickness different from one another;
• wherein the quantum well regions comprise:
• a first quantum well region, a second quantum well region and a third quantum well region;
• a wavelength of a gain peak of the second quantum well region is greater than a wavelength of a gain peak of the first quantum well region but is less than a wavelength of a gain peak of the third quantum well region;
• wherein when the temperature rises, the injection current of the first quantum well region is increased to compensate gain spectrum drift resulted from rise of the temperature;
• and
• when the temperature drops, the injection current of the third quantum well region is increased to compensate gain spectrum drift resulted from drop of the temperature.